Modern Concept Science and Technology 10 New

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 97 ACTIVITY 3 DNA Forensic Laboratory Pvt. Ltd. sells DNA test kits Online. Try one if possible. Role of DNA testing i. DNA testing is done to check or rule out possible chromosomal disorders or genetic disorders. ii. Doctors can prescribe medicines or customize treatment based on a DNA test of a person. iii. DNA test can be done to test if someone is biologically related to a child or not. Example: DNA paternity testing. iv. Many uses DNA testing to check their ancestry nowadays. v. It also helps to learn about various things about evolution. vi. It is used to test if an organ donor and receiver have a genetic match. vi. DNA testing is widely used in an investigation. It is used to solve crimes. In case there is a suspect, the DNA of the suspect is tested. The result is then compared to the DNA test result of any samples collected from the crime scene. Then based on the comparison of the two results judge can conclude the case. For example, let’s say there is a robbery. Then the criminal investigation department will collect any sample from the crime scene. For example, it may be hair, blood, sweat, tears and fingerprints. They will run a DNA test. Then they will do further investigation and find some suspects. They can do a DNA test on the suspects and tally the results. They can conclude if the suspect is a criminal or not. Usually, DNA testing helps to solve rape and murder cases. Question to think If a child detached from his parents in early age do not know who his parents are? How can he try to find the parents? Breeding Reproduction is the production of a new individual organism from its parent or parents. Every living thing reproduces sexually or asexually. During sexual reproduction, two parents are involved. One of them is male and other one is female. The male and female organisms of same species take part in sexual reproduction. So, the way in which plants and animals produce new organisms through sexual reproduction is called breeding. The organisms that take part in breeding are called breeding pairs. Breeding in the wild means a natural process in which wild animals reproduce. Sexual reproduction in plants is also considered breeding. It is popular in animal husbandry too. Humans select special traits of a certain organism and use them for breeding new organisms. FACTS WITH REASON Most wild animals breed in spring. Most wild animals breed in spring because it's warm and enough food is available in the forest during spring. The Central Police Forensic Science Laboratory (CPFSL) of Nepal Police started DNA testing in Kathmandu in 2015. MEMORY TIPS Genetic variation is necessary to make progress in breeding successive generations. MEMORY TIPS

98 genetic te cHnology Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur ACTIVITY 4 Visit a cow farm and observe the cows. Make a questionnaire and ask farmers. Collect information on purebred cows and crossbred cows. List out their characteristics. Selective breeding Humans can choose to keep animals or plants with suitable characteristics and discard the other. For example, humans captured and tamed less aggressive wolves. After thousands of years, it gave birth to new species the dogs. Similarly, cauliflower is a highly modified version of cabbage of a mustard family. Cauliflower exists because farmers choose the seed of plants that had better flower and bred for many years. It is called selective breeding. The process in which humans identify certain special traits in an organism and take steps to breed them so that a new organism will have those traits is called selective breeding. It is also called artificial breeding. Selective breeding helps an organism to evolve faster. Animal breeding is widely used in animal husbandry. It helps us to grow hens that can give a large number of eggs or meat. We can get sheep with lots of meat or wool. Farmers can fertilize their cows with another breed of cow that gives lots of milk. Plant breeding is also in practice since ancient times. It helps farmers to grow high-yielding varieties of crops. It is also used to grow plants that can resist viruses, bacteria, fungi and drought. Breeding back helps to re-assemble genes to give birth to plants or animals that are already extinct. Demerits of selective breeding i. As a result of selective breeding plants and animals which have only one type of genetic characters grow in large population. ii. Genetic diseases and infectious diseases can transfer from generation to generation. iii. Selective breeding is also called artificial selection because it is done by the human choice. iv. It may reduce biodiversity . FACTS WITH REASON Selective breeding affects biodiversity. Selective breeding affects biodiversity because we select only those animals and plants which have desired characters and discard others. In this process, some animals and plants which have one or few bad characters are left for breeding. It may extinct these animals and plants. Methods of selective breeding Selective breeding can be carried out in multiple ways. The most common techniques of selective breeding are given below: Mice used in lab experiments are often inbred, as similar genetic structures enable experiments to be repeated. MEMORY TIPS

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 99 Inbreeding Inbreeding is the act of breeding between males and females who are closely related genetically. It is inbreeding between first-degree relatives. Inbreeding helps to bring uniformity in characteristics of that organisms. It is done to preserve certain trait of organisms which is desirable to humans. They are also called pure trait. For example, if we have a cow that is very healthy and gives a lot of milk, we can fertilize it with a bull which is genetically identical to our cow. So that newborn cow can also give a lot of milk. However, inbreeding has lots of side effects. For example, since male and female from same family is breeding, recessive characteristics can be seen in children. The offspring may be unhealthy physically and mentally. Inbreeding is considered a crime in human beings. Some examples of pure inbred are Siamese cat, Labrador retriever dog, etc. FACTS WITH REASON Inbreeding is not good for humans. Why? Inbreeding is not good for humans because the recessive characteristics are observed. The offspring suffer from genetic disorders, gene pool decreases and children can be violent. ACTIVITY 5 Finds seeds of a dwarf pea plant and the seeds of a tall pea plant. Grow them on same farm. When they are matured cross-pollinate them. Collect the seeds and sow them to grow new pea plants. What can be observed? What is the advantage of this selective breeding? Line breeding Line breeding is the act of breeding between males and females who are second-degree relatives of each other. It helps to increase genetic purity among animals and plants. For example, let’s say a goat gave birth to two female kids. Two farmers take away each of them. After few years both farmers have their own herd of goats. If he-goat of the first farmer and she-goat of the second farmer mate, it is called line breeding because they are a distant relative. It helps to counter the side effects of inbreeding to some extent. Self pollination The transfer of pollen grains from anther to stigma of the same flower or flowers of the same species is called self pollination. It results almost same types of offspring. Out-crossing Out-crossing is the act of breeding between males and females who are unrelated for at least four to six generations. It is also called out breeding. It helps to import distantly related genetic materials into the breeding line. As a result, it improves genetic diversity because organism of different bloodline is breeding pairs. For example, The Belgian blue cow is the result of out crossing between a local cow of Belgium with an imported cow from England. If a farmer uses out crossing multiple times, then all the good traits of the organism will be lost.

100 genetic te cHnology Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Cross breeding Chromosomes exist in pairs. If both of the chromosomes of an allele are identical, then the organism is called purebred. All individuals of a purebred have same observable characteristics. If a purebred male and a purebred female of two different species of same genus are crossed to produce new offspring, it is called crossbreeding. The organism thus produced contains each allele from both parents. Since the chromosomes of an allele in this organism are different, the organism is called a hybrid or crossbred. The offspring from different species of purebred parents are often called crossbreds. Some examples of crossbreds are given below. Mule : The horse and the donkey are two different species. When a male donkey and a female horse mate to produce offspring, a mule is born. It is sterile, can carry load like donkey and run like horse. Hinny: When a male horse and a female donkey mate to produce offspring, a hinny is born. It is infertile. Liger: The hybrid obtained from male lion and female tiger is called liger. It is bigger than their parents and behave like lion. Tigon: The hybrid obtained from male tiger and female lion is called tigon. It is very small than their parents. They look like tiger but behave mostly like lion. Beefalo: The hybrid obtained from American Bison and bull is called beefalo. They are fertile. It is done for more meat. Zebroid: The hybrid obtained from zebra and horse is called zebroid. They are infertile. Pomato: The hybrid obtained from tomato and potato is called pomato. They give tomatoes outside the soil and potatoes inside the soil. Mule, and Hinny are infertile. They do not give birth. MEMORY TIPS Figure: Mule Figure: Hinny Figure: Liger Figure: Tigon Figure: Beefalo Figure: Zebroid Figure: Pomato

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 101 The crossing between lemon and orange gives Meyer lemon which is a hybrid. MEMORY TIPS Advantages of crossbreeding Crossbreeding is in practice in animal husbandry and agriculture. Various species are crossed to produce hybrids with desirable traits. Some of the major advantages of crossbreeding are discussed below : i. It helps to improve the quality of plants and animals so that farmers can get more in return from their farms. ii. Crossing between local breed and foreign breed with desirable traits makes new offspring stronger. iii. Cross breeding between two species helps to cancel out weak traits of each species. iv. The crossbred animals are heterotic. It means hybrid organisms have better improved biological qualities. A crossbred can have better weight, height, adaptation, disease resistance, etc. FACTS WITH REASONS Farmers breed their nanny goats with selected bucks only. Farmers seek profitable production from their farms. To get the off springs of the nanny goat with desirable traits like healthiness, strength, size etc. for more meat production, farmers breed them with selected bucks only. ACTIVITY 6 Observe different crossbred dogs. Do they have same traits? Discuss. Beware of dogs. Disadvantages of crossbreeding Crossbreeding can be performed by anyone. We can just find a male and female of two different species, breeds or varieties of plants and animals and breed them together. As a result crossbreeding occurs. It occurs between various organisms naturally without human aid too. However, it is better if professionals handle crossbreeding because many things can go wrong while crossbreeding. FACTS WITH REASONS A crossbreed may be sterile. A crossbreed have chromosomes from two different species which do not match up, so it does not have viable sex cells. Which can not produce sperms and eggs. Some disadvantages of cross breeding are: i. A random cross breeding can cause back crossing to the original breed with inferior quality. ii. Cross breeding can give birth to aggressive and violent offspring or vice versa. It is hard to predict their nature. Crossbred dogs live longer than purebred dogs. MEMORY TIPS

102 genetic te cHnology Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur iii. It's very difficult to predict the body size of offspring when they become adults. For example, a cross between a lion and a tiger produces a liger which is very big. iv. Usually, animals die while giving birth because the offspring can have bigger heads or bodies inherited from bigger male breeds of animals. v. The price in the market for hybrid is comparatively less than pure breeds. vi. Due to continuous cross breeding some pure breeds may extinct. In vitro fertilization (IVF) In vitro fertilization is an assisted reproductive technology. It is usually used to treat infertility in females as well as males. IVF was first successfully used to treat human infertility in 1977 at Bourne Hall in Cambridge, England. In this process, usually, an ovum is collected from a female and sperm is collected from a male. Then the ovum and sperm are fertilized in the glass tube, beaker or Petri dishes in a controlled environment. When the zygote changes into an embryo, it is placed in the uterus. The embryo will now grow normally in the uterus and change into a foetus. This technology is called in vitro fertilization. The process in which ovum and sperm are fertilized outside the female body in the glass vessels is called in vitro fertilization. To practise in vitro fertilization a woman must take medicines to stimulate the ovary. She is under sedation by consuming sedative drugs. The stimulated ovary releases many eggs which are collected by the doctors. The sperm is collected on the same day. The sperm is washed. The ovum and sperm are fertilized under a suitable condition in a petri dish. Doctors check embryos for diseases and genetic disorders. After a few weeks, it is transferred to the uterus. A blood test after two weeks helps to confirm if the embryo is either growing well or rejected. Conditions when doctors suggest in vitro fertilization i. If the fallopian tube is absent or is suffering from untreatable diseases, IVF is suggested. ii. If a woman is suffering from endometriosis disease where extra tissues are growing in the uterus and fallopian tube. iii. If males have low sperm count or any other defect related to sperm. iv. If the male is not producing sperm at all and sperm should be collected by surgery. v. If a man or woman is suffering from genetic diseases that prevent fertilization. FACTS WITH REASONS Ovary is stimulated using drugs for IVF. Ovary is stimulated using drugs for IVF because it helps to collect many ova at once in a syringe otherwise only one ovum is produced at a time. In vitro fertilization is the most successful fertility treatment currently available. MEMORY TIPS Figure of IVF

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 103 ACTIVITY 7 Make a collage model of invitro fertilization. Importance of in vitro fertilization i. It helps infertile couples to conceive who cannot conceive naturally. ii. It is the most successful method to treat infertility. iii. It can help same-sex people or single women to be a parent. iv. It helps to diagnose fertilization problems. v. Embryos are genetically tested and discarded if any genetic disorders or diseases are found. Disadvantages of in vitro fertilization i. IVF can be unsuccessful. It is based on the age of the mother and reproductive history. The younger woman has more chance of successful IVF than the older one. The woman who was previously pregnant has more success rate than those who were never pregnant. ii. The chances of miscarriage range from 15 to 25 %. iii. It may show multiple side effects. iv. Since there is a chance of failure, doctors insert multiple embryos into the uterus. So multiple births are common. v. It is expensive. vi. Some people find it unethical. vii. It may give pre-matured and under weight baby. viii. In this process the woman may have psychological stress. Artificial insemination Artificial insemination is an assisted reproductive technology. It is used to treat infertility if couples are not able to conceive naturally. Artificial insemination was first successfully used to treat human infertility in 1790. The first successful artificial insemination by a donor was performed in 1884. The first sperm bank was started in the 1950s. A sperms bank is a place where semen is kept in cold storage for use in artificial insemination. In this process, the women’s menstrual cycle is observed carefully. Ovulation kits, ultrasound, blood tests, softness of nose of cervix etc. are used to determine the timing of the ovulation cycle. Sometimes drugs are used to stimulate the menstrual cycle. Ova are collected by using a syringe. Sperm is collected from a healthy man when he remains on abstinence for at least three days. If the husband or sperm donor is sick sperm is not collected. If the private donor donates the sperm, it is not stored or frozen. It is supplied fresh to the woman. In case sperm The first IVF baby (Louise Joy Brown) from Lesle Brown and John Brown born in 25 july 1978. Similarly, in Nepal the first IVF baby (Om Mani Tamang) from Rajendra Tamang and Sandhya Tamang born in 3 march 2005. MEMORY TIPS In animal husbandry, mass breeding can be done by using AI. MEMORY TIPS Figure of AI

104 genetic te cHnology Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur is from a sperm bank it is washed, frozen and quarantined. Sperm can be stored in a special container and stored in the sperm bank. A sperm extender is added which helps to preserve fertilizing ability of sperm. It also helps in freezing, storing and transporting sperm in the container. Then the semen is donated to the woman who needs it. Sperm is introduced to a woman’s vagina, cervix or uterus. If the raw unwashed sperms or donated sperms from a sperms bank are introduced into the vagina it is called intracervical insemination. It is the easiest form of artificial insemination. It can be performed by the woman herself. Otherwise, doctors will introduce it to the vagina in fertility clinics. Sperm will then swim into the cervix and then to the uterus. It will travel further into the fallopian tubes and fertilizes the egg. Women should lie still for about 30 minutes so that sperm can swim easily toward the egg. If the washed sperm is introduced directly into the uterus, it is called intrauterine insemination. It has more success rate than intracervical insemination. Sometimes washed sperm is also introduced into the fallopian tubes to increase the success rate. FACTS WITH REASON Sometimes doctors introduce sperm directly into the uterus. Sometimes doctors introduce sperm directly into the uterus because it makes the trip shorter for sperm. It increases the success rate. ACTIVITY 8 Draw a figure of artificial insemination in cow. Also list the farm animals in which artificial insemination are widely used. Conditions when doctors suggest artificial insemination are if: i. The patient is suffering from endometriosis. ii. If the sperm count is low. iii. If sperm mobility is less. iv. If sperm cannot penetrate the cervix. Advantages of artificial insemination i. It helps a woman to conceive if she is not conceiving naturally. ii. It helps single women, widowers, lesbians etc. to be a parent. iii. It is cheaper than in vitro fertilization. iv. It helps a man to be a parent in case his sperm count is low. v. In animal husbandry, it does not require to keep animal in the farm. vi. It reduces STD and increases rate of fertility. vii. It avoids injury in animals which frequently occurs during male and female mating. Doctors may recommend artificial insemination to a woman under the age of 35 if she does not conceive after a year of unprotected mating. MEMORY TIPS

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 105 FACTS WITH REASON How does artificial insemination (AI) help farmers? In animal husbandry, it does not require to keep male in the farm. It reduces cost. It reduces STD and increases rate of fertility. It avoids injury which frequently occurs during male and female coupling. We can carry sperms for a long distance. Disadvantages of artificial insemination i. It needs skilled manpower to do it. ii. It can be unsuccessful. iii. Dirty instruments can cause infection. iv. To prepare artificial insemination, it needs more time than natural fertilization. HOT SKILL HIGHER ORDER THINKING SKILL 1. Do changes in genetic make-up affect the traits of organisms? Yes, the changes in genetic make-up affect the traits of an organism because genes contain characteristics that determine our bodies. The changes in genes can easily alter physical appearances, disease resistance, physical abilities and intelligence. 2. Can DNA testing be used to solve criminal investigations? DNA testing is a technology which is used to count chromosomes and identify changes in genes and genomes. It can be used to identify a person accurately. So, if there is any material collected from the crime scene that contains DNA, the DNA testing can exactly tell who the criminal is or is not. The sample from the crime scene such as blood, sweat, nails, hair, saliva, etc. are sent to the laboratory. The DNA test is carried out to identify the criminal. DNA testing of the suspect is also done. Two reports are tallied to see if the suspect is guilty or not. 3. The cattle produced from inbreeding were sick and weak. When a cow and bull were mated that were separated by a few generations, the offspring were healthy. Discuss the reasons. The cattle produced from inbreeding were sick. The main reason for sick cattle from inbreeding is they have a very small gene pool. But when a cow and bull were mated that are a few generations apart, the offspring were healthy. It is because they are a few generations apart, and they contained a larger gene pool. In this process, the better dominant characteristics appeared in the offspring. 4. If two cattle from the same parents bred together, what is it called? Why should farmers avoid it? If two cattle from the same mother are bred together, it is called inbreeding. Farmers should avoid inbreeding, especially in animals because of the following causes: i. Offspring from inbreeding is usually violent. ii. Most offspring die early. iii. Most of them are sick. iv. They have lots of recessive characters. 5. Mrs Krishna Kumari has a healthy and big buffalo that gives lots of milk. She wants to breed siblings he-buffalo and she-buffalo so that the good traits can be transferred to the offspring. Did she make the

106 genetic te cHnology Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur right decision? Explain to her why is it a wrong idea. Also, explain to her that she should find a healthy he-buffalo which is not related to her she-buffalo with reasons. Mrs Krishna Kumari has a healthy and big buffalo that gives lots of milk. She plans to breed sibling hebuffalo and she-buffalo so that good traits can be transferred to the offspring. However, it is not a good idea. We should tell her that breeding two siblings are called inbreeding. Inbreeding causes recessive characteristics to appear in organisms. Offspring can be weak, prone to diseases and cannot adapt to changing environments. Instead, she should practice line breeding. It means finding a healthy he-buffalo which is separated for a few generations. It can be a distant cousin. It contains more gene pools. So, offspring can have better genetic make upand physical traits. Outbreeding is also a good solution to her problem. It means finding a healthy he-buffalo which is not genetically related to her buffalo. It provides a wide range of gene pools. The offspring will be in better health, can adapt easily to the environment and has lots of good traits. 6. Differentiate between a tigon and a lion. The differences between a tigon and a lion are: SN Tigon SN Lion 1 It is a crossbred. 1 It is not a crossbred. 2 It is sterile. 2 It is fertile. 7. We should be very careful while collecting the sample for the DNA test. We should be very careful while collecting the sample for the DNA test so that we could collect sufficient DNA for the test. We should also be aware that we should not mix samples from other sources than the required ones. 8. A child was born from a rape victim. How can the father of the child be known? If a child born from a rape case, or a child who does not know his biological parent can track the parents from DNA testing. DNA testing can accurately track down the parents. 9. Mr. Bhakta is an infertile man. He wants to have some kids with his wife. He has already tried many herbs and ayurvedic medicines. He has also prayed and visited wizards but all in vain. What suggestions can we offer him so that he will be a father of some children? Despite using many ayurvedic medicines and herbs or visiting wizards, praying, etc. Mr. Bhakta is still unable to be a father of a child. The probable causes may be, his testicles are underdeveloped, sperm are weak, sperm count is low or sperms are immotile. So, we can suggest using assisted reproductive technology to fertilize his wife. i. He can use artificial insemination. He should collect sperm and give it to the doctors. Sperm will be washed, concentrated and introduced into the mouth of the cervix of his wife. The sperm could swim to the fallopian tube and fertilize. ii. If intracervical insemination failed, the doctors can collect sperm from his testicles directly through the syringe, wash them and introduce them to the uterus or fallopian tube directly in his wife. It might help to conceive. iii. In case artificial insemination fails, he can use in vitro fertilization. The ova are collected from his wife. Then it is fertilized with his sperm in a petri dish. The embryo is developed in a Petri dish. Healthy embryos are planted in his wife's uterus.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 107 iv. Lastly, he can use sperm from the sperm bank to fertilize his wife. Above mentioned assisted reproductive technologies could probably help him to be a father of a child. 10. Miss Sasikala does not want to get married but wants to be a mother. She is considering conceiving through artificial insemination. Explain possible risks of artificial insemination and suggest some methods to avoid those risks. Miss Sasikala does not want to get married but wants to be a mother. She has consulted doctors about artificial insemination. It would make her a mother but there are certain disadvantages to the technology. Some of them are discussed below: i. There is a chance that artificial insemination will fail. She should visit experienced doctors for the procedure. ii. Sperm could transfer diseases into her body. It would be wise for her to find a healthy sperm donor with no infectious diseases or genetic defects. It is wise if she uses sperm from a sperm bank because stored sperm are already checked for diseases. iii. Dirty tools can cause infections in the uterus. So, she should make sure that doctors and nurses use clean and sterilized tools during the process. iv. She should consider receiving sperm from a young and healthy donor. 3 STEPS 3 STEPS EXERCISE EXERCISE STEP1 1. Select the best answers from the given alternatives. a. If two cattle from the same parents bred together, what is it called? i. cross breeding ii. artificial insemination iii. linebreeding iv. inbreeding b. What do vaccines contain? i. RBC, WBC and platelets ii. active virus, harmful chemicals, bacteria iii. antibodies, antibiotics, penicillin iv. weakened virus, genes of virus, parts of the virus c. Which of the following cannot be proved by DNA testing? i. genetic disorders such as Down’s syndrome ii. tell the gender iii. identify the dead bodies from the plane crash iv. identify real husband and wife d. If a jersey cow is bred with an acchami cow, what type of breeding is it? i. inbreeding ii. line breeding iii. cross breeding iv. outcrossing

108 genetic te cHnology Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur e. Pet shops cross different pure-bred dogs to produce new puppies. What kind of animals are they? i. purebreds ii. crossbreds iii. hybrids iv. clones f. How are mules born? i. from the male mule and female mule. ii. cross-breeding between a female donkey and a male horse. iii. cross-breeding between a male donkey and a female horse. iv. from crossbreeding of mole and horse. 2. Define the following terms with required examples. a. Genes b. Genetic engineer c. Genetic technology d. DNA testing e. Reproduction f. Breeding g. Selective breeding h. Inbreeding i. Line breeding j. Outcrossing k. Purebred l. Crossbred m. In vitro fertilization n. Artificial insemination o. Intracervical insemination p. Gene therapy 3. Answer the following questions in very short. a. Which assisted reproductive technology is popular in animal husbandry? b. To whom, in vitro fertilization is suggested? c. Which types of assisted reproductive technologies can be used for a man who has underdeveloped testicles, weak sperm, sperm count is low or sperms are immotile? d. Write one banned application of genetic technology. e. In which breeding technique, males and females from different breeds are crossed? f. What are genetically modified organisms? g. What is it called if a zygote is introduced into the uterus? STEP2 4. Give reasons. a. Genes are called hereditary units. b. Genetic engineers usually cut, remove or add genes to chromosomes. c. Doctor’s test DNA of the foetus. d. Genetic engineers introduce genes of viruses in certain foods and plants.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 109 e. Genetically modified plants should not be allowed to spread in a natural ecosystem. f. Modifying genes in the human embryo is banned. g. DNA testing is widely used in the investigation. h. Animal breeding is widely used in animal husbandry. h. Line breeding is better than inbreeding. i. Farmers use sperm of jersey or Holstein cows for artificial insemination of a local cow. j. Blood test is performed after two weeks of in vitro fertilization. k. Sperm should be washed before using it for in vitro fertilization. l. Women should consume certain drugs if they want to use IVF. m. Women should lie still for about half an hour after artificial insemination. n. Multiple embryos are introduced in the uterus during IVF. 5. Differentiate between the following. a. Inbreeding and line breeding b. Outbreeding and cross-breeding c. Purebred and cross bred d. Artificial insemination and invitro fertilization 6. Answer the following questions in short. a. What characteristics are usually determined by genes? b. What kind of genetic technologies are used in agriculture? c. Write down the examples of genetic technology in medicine. d. Genetic technology can be used to do unethical experiments. What are the measures against genetic technology? e. How is DNA testing used in a criminal investigation? f. How does selective breeding help in evolution? g. Even though inbreeding helps to collect superior traits of organisms, it still has some drawbacks. What are the drawbacks of inbreeding? h. Inbreeding is harmful because recessive traits appear in organisms. So, farmers are suggested to practice line breeding. Write any two reasons to do so. i. Under what situations in vitro fertilization is preferred? j. Write the importance of in-vitro fertilization. k. What are the challenges for invitro fertilization? l. What is the disadvantage of crossbreeding? m. The cattle produced from inbreeding were sick and weak. When a cow and bull were mated that were separated by a few generations, the offspring were healthy. Discuss the reasons.

110 genetic te cHnology Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur 7. Answer the following questions on the basis of the given figure. i. Which assisted reproductive technology is shown in the diagram? ii. Under what condition it is preferred? Write any two. iii. Why are sperms washed within one hour for this process? STEP3 8. Answer the following long questions. a. Genetic technology is a new field of science. Discuss its importance and application in society. b. Genetic engineering can modify the traits of organisms. It is a very dangerous technology. What are the potential issues of genetic technology? c. DNA testing can accurately identify the person. How is DNA testing done? What is its application in society? d. Selective breeding is not a new technology. There are multiple methods for selective breeding with their own pros and cons. Write a short note on methods of selective breeding. e. Mr. Harka is keeping cows in his house for ages. He is wondering if he should request a veterinary doctor to inseminate his cow with sperms of Jersey cow. Explain to him the concept of cross-breeding, the benefits he can receive and also the potential side effects of cross-breeding. f. How can an infertile couple have a baby? Introduce in vitro fertilization techniques to them. Educate them about the merits and demerits of IVF. g. Let’s suppose there is a lesbian couple. They have tried artificial insemination using sperm from a sperm bank but failed twice. Which assisted reproductive technology will the doctor suggest for them now? Explain the procedure of that technology. h. Mrs. Radha cannot conceive despite unprotected mating. She has heard about artificial insemination but is worried that she might catch diseases or die during the process. Clarify the concept of artificial insemination, its procedure, advantages and side effects to her. So that she can decide either to use or not use this technology. i. How do artificial insemination benefit farmers? j. How and why is intrauterine insemination carried out?

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 111 Key terms and terminologies of the unit 1. Circulatory system: The organ system in human body which supplies food, oxygen, hormone, etc. to the different parts of the body and carries away metabolic waste to the site of excretion with the help of blood is called blood circulatory system. 2. Blood: Blood is a heterogeneous, red coloured, viscous liquid connective tissue that is made up of 55% plasma and 45% blood cells. 3. Plasma: Plasma is a yellow coloured semi-transparent liquid present in the blood. 4. Red blood corpuscles: Red blood cells (RBCs) are red-coloured, biconcave, enucleated structures floating freely in the blood. 5. White blood corpuscles: White blood corpuscles (WBCs) are irregular blood cells which have nucleus and other cell organelles. 6. Platelets: Platelets are non-nucleated, irregular, colourless, round or oval blood cells found freely suspended in the blood plasma. 7. Anaemia: Anaemia is a condition which is caused due to the lack of RBCs or haemoglobin in the blood. 8. Haemophilia : Haemophilia is a condition in which blood clotting delays in the cuts and wounds due to the absence of blood-clotting chemicals. 9. Leukaemia : Leukaemia is a condition in which a person has excess number of WBCs in their body. Sequence of Curriculum Issued by CDC  Introduction to the human blood circulatory system  Structure and function of different parts of human blood circulatory system  Blood circulatory system in human body  Introduction and identification of blood group  Investigation of heartbeat and pulse  Blood pressure, blood sugar and uric acid  Heart attack: introduction, causes, measures to control and curative method (angiography and bypass surgery) UNIT Physiological Structure and Life Process 5 Estimated teaching periods Theory Practical 9 3 Karl Landsteiner is well known as the father of transfusion medicine for his research on the blood group system. He was born in Austria-Hungary on 14th June 1868 and died on 26th June 1943. He was a biologist, physician and immunologist. He distinguished main blood groups in 1900. He also discovered the Rhesus factor in RBC. He also discovered the polio virus. He was honoured with Nobel Prize in Physiology or Medicine in 1930. Karl Landsteiner About the Scientist

112 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur 10. Leukopenia : Leukopenia is a condition in which a person has reduced number of WBCs in their body. 11. Blood-clotting : The process of formation of solid mesh at the site of cuts and wounds is called bloodclotting or blood coagulation. 12. Blood vessels : The elastic tubes and pipes through which blood flows are called blood vessels. 13. Arteries : Arteries are thick-walled blood vessels that carry blood away from the heart. 14. Veins : Veins are the thin-walled blood vessels that carry blood towards the heart. 15. Capillaries : Capillaries are hair-like, extremely narrow and thin-walled blood vessels. 16. Pericardium : The double-layered membranous structure that covers the heart is called the pericardium. 17. Pericardial cavity: The two layers of the pericardium are close to each other forming a gap called pericardial cavity. 18. Pericardial fluid : The lubricating fluid present in the pericardial cavity is called the pericardial fluid. 19. Tricuspid valve : The valve between the right auricle and right ventricle is called tricuspid valve 20. Bicuspid valve : The valve present between left auricle and the left ventricle is called bicuspid valve. 21. Pulmonary valve : The valve present between pulmonary artery and right ventricle is known as pulmonary valve. 22. Aortic valve : The valve present between aorta and the left ventricle is known as the aortic valve. 23. Blood pressure : The pressure exerted by blood on the walls of the arteries when the left ventricle contracts and relaxes is known as blood pressure. 24. Systolic blood pressure : Systolic blood pressure is the measure of maximum pressure in the arteries when left ventricle contracts. 25. Diastolic blood pressure :Diastolic blood pressure is the measure of minimum pressure in the arteries when left ventricle relaxes. 26. High blood pressure : High blood pressure is a condition in which blood pressure is equal to or greater than 140/90 mm of Hg for more than two days. 27. Heart beat : A heart beat is a continuous rhythmic beat throughout the life which is produced due to complete contraction and relaxation of the heart muscle. 28. Arterial pulse : The repetitive jerk felt at the major arteries of the body due to the pumping action of the heart is known as the arterial pulse. 29. Pulmonary circulation: The type of circulation in which blood flows from right ventricle to the lungs and then to the left auricle is called pulmonary circulation. 30. Systemic circulation : The circulation of blood from left ventricle to the right auricle of the heart through body tissues (except lungs) is called systemic circulation. 31. Insulin : Insulin is a hormone secreted by pancreas that helps in glucose utilization and control. 32. Diabetes : The condition in which body becomes unable to maintain normal glucose level due to the lack of insulin is called diabetes. 33. Uric acid : Uric acid is an antioxidant which helps to remove toxic materials from our body and also protects the inner walls of the blood vessels. 34. Gout (uric acid) : Gout is a form of arthritic disease which is characterized by the deposition of uric acid crystals in the large joints of body like knee, toe, etc. 35. Heart attack : The blockage of the flow of pure blood into the cardiac tissues of the heart is called a heart attack. 36. Bypass surgery: Bypass surgery means finding alternative arteries to supply blood to the cardiac tissue of the heart when the majority of blood vessels are blocked or are very narrow. 37. Angiography: Angiography is an effective way to treat a heart attack. It uses an x-ray imaging technique to find the blood clot. After that a catheter or a tiny balloon is used to open the blockage.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 113 Human blood circulatory system Look at the given pictures. What do they suggest to you about circulation of body fluids in human body? Can you suggest why blood oozes out of our body during cuts and wounds as shown in the first picture? What is the doctor doing in the second picture? In the first picture, the red coloured fluid oozing out from the cut in the finger is blood. It oozes out for a couple of minutes and then stops. In the second picture, the doctor is listening the heart sound by stethoscope. The heart continuously beats inside our chest. Why does it beat? All these questions are related to the blood circulatory system of our body. In this unit, we will attempt to answer these questions. Blood oozing out from a cut in finger Doctor using a stethoscope to listen the heart and lungs sound in a child When we feel headache, we take a painkiller. After sometime we get relief. This is because the chemicals present in the painkiller reach to the head through blood circulatory system. Similarly, every organism needs food to live. The food we eat is converted into simpler form inside the digestive system. The digested food is absorbed and then mixed in the bloodstream. The nutrients present in the digested food are transported to the different parts of the body through blood circulation. Along with the nutrients, blood circulatory system also conducts oxygen, carbon dioxide, hormone, medicines, waste product, etc. from one part of the body to the next. Thus, the organ system in human body which supplies food, oxygen, hormone, etc. to the different parts of the body and carries away metabolic wastes to the site of excretion with the help of blood is called blood circulatory system. The blood circulatory system is also responsible for maintaining constant body temperature, chemical composition, pH value, etc. The blood circulatory system consists of three main parts. They are blood, blood vessel and heart. The heart is the main pumping organ of the blood circulatory system. The arteries, veins and capillaries are the pathways through which blood flows. Similarly, the blood is a main medium to circulate various materials throughout the body. Functions of the circulatory system i. Blood circulatory system transports oxygen, nutrients, hormones, medicines, etc. to the various parts of the body. ii. It carries different kinds of metabolic wastes to the site of excretion. iii. It regulates the constant body temperature. iv. It balances chemical composition, pH value, water, minerals, etc. in the body. Similar to blood circulatory system in human beings, the conducting system made up of xylem and phloem is responsible to conduct water, minerals and food materials in the plants. MEMORY TIPS

114 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Blood Blood is a heterogeneous, red-coloured, viscous liquid connective tissue that is made up of 55% plasma and 45% blood cells. It continuously circulates throughout the body and never stops. Some major characteristics of blood are as follows. i. Colour: The colour of blood is blackish red, scarlet (dark reddish orange) or blue depending upon its type. Pure or oxygenated blood is scarlet in colour while deoxygenated blood is blackish red. But, the deoxygenated blood in veins looks blue from outside because of the reflection of blue light from the walls of the veins. ii. Volume: In an adult, the total volume of blood is about 5.5 litres in average. The total volume of blood depends upon the water content in it. iii. Specific gravity and pH: Blood is slightly heavier than pure water. Its specific gravity or relative density is 1.05 to 1.06. It is alkaline in nature with pH value 7.35 to 7.45. Composition of Blood Blood is a heterogeneous fluid. It is composed of two main components. They are 55% blood plasma and 45% blood corpuscles. Blood corpuscles are of three types. They are red blood corpuscles (RBC), white blood corpuscles (WBC), platelets. Blood plasma Plasma is a yellow coloured semi-transparent liquid present in the blood. It forms about 55% of the total volume of blood. It contains upto 90% water, 8% proteins and 2% respiratory gases, nutrients, hormones, minerals, salts, carbohydrates, antibodies and other chemicals. Without blood corpuscles, plasma looks yellow coloured. The plasma transports all the dissolved substances in different parts of the body. The blood corpuscles, viz. red blood cells, white blood cells and platelets are immersed in the plasma along with other substances. Functions of Plasma There are many functions of plasma. Some of the major functions are listed below: Blood is slightly heavier than water and slightly alkaline in nature. But we feel salty taste while tasting it. MEMORY TIPS Plasma Red blood cell White blood cell Platelet Composition of blood Separation of blood components by centrifugation

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 115 i. Plasma transports digested food, minerals, hormones, antibiotics, water, etc. to the different parts of the body. ii. It transports waste products to the site of excretion. iii. It maintains constant body temperature. iv. It maintains water, chemical composition and pH value of the blood. v. It contains fibrinogen which plays an important role in blood clotting. Blood corpuscles or cells Blood corpuscles occupy about 45% of the total volume of the blood. There are three kinds of blood corpuscles in the blood. They are red blood cells, white blood cells and platelets. Red Blood Cell (RBC) or Erythrocytes Red blood cells (RBCs) are red coloured, biconcave, enucleated structures floating freely in the blood. They carry a red pigment at their centre called haemoglobin. The matured RBCs do not have a nucleus except in camels. The whole blood appears coloured because there are millions of RBCs in it. A single haemoglobin molecule is made up of 4% haemin (iron) and 96% globin (protein). The function of RBC is to transport oxygen to all parts of the body and to collect carbon dioxide to excrete out into the lungs. There are 45 lakhs to 50 lakhs RBCs in 1 mm3 of blood. In every second, about 20 lakhs RBCs are formed and the same number is destroyed. When RBCs die, their iron content present in haemoglobin is reused by the liver to make a chemical called bilirubin. RBCs are formed in the bone marrow of the bones such as vertebrae, ribs, skull, etc. and die in the liver and spleen. Their average life span is 90 to 120 days. Blood is called a heterogeneous mixture, why? Blood is called a heterogeneous mixture because the blood plasma contains bigger-sized blood corpuscles Why is blood red in colour? Blood is red in colour due to the presence of red pigment called haemoglobin. Blood without RBCs has light yellow colour, why? In absence of RBCs, blood has only WBCs, platelets and blood plasma. The blood plasma comprises about 55% of the total blood. It is a transparent yellow liquid. Therefore, blood without WBCs has light yellow colour. FACTS WITH REASON Oxyhaemoglobin and deoxyhaemoglobin The blood which carries oxygen is known as oxygenated blood. At the centre of RBC, haemoglobin molecule is present. This haemoglobin molecule combines with oxygen and transports it to the tissue. One haemoglobin molecule can carry up to four molecules of Red blood cells White blood cells Plasma Platelets Blood vessel Blood cells In an adult man the number of RBCs ranges from 50 lakhs to 55 lakhs and in an adult woman it ranges from 45 lakhs to 50 lakhs in per cubic millimetre blood. MEMORY TIPS

116 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur oxygen. The haemoglobin which carries oxygen is known as oxyhaemoglobin. The blood which carries carbon dioxide in the body is known as deoxygenated blood. During circulation, haemoglobin transports oxygen to the cells and receives carbon dioxide from there. The collected carbon dioxide is transported to the excretory organ to eliminate from the body. A haemoglobin can combine with four molecules of carbon dioxide. The haemoglobin that carries carbon dioxide is called deoxyhemoglobin. White blood cells (WBC) or Leucocyte White blood corpuscles (WBCs) are irregular blood cells which have nucleus and other cell organelles. They show amoeboid movement in the blood plasma. They do not contain haemoglobin. WBCs are of two types. They are granulocytes and agranulocytes. The white blood corpuscles which have granules in their cytoplasm are called granulocytes or granular leukocyte. There are three types of granulocytes. They are neutrophils, basophils and eosinophils. Similarly, the white blood corpuscles which do not have granules in their cytoplasm are called agranulocytes or agranular leukocyte. There are two types of agranulocytes. They are lymphocytes and monocytes. Function of WBCs The main function of WBCs is to kill microorganism present in the blood. They also engulf the foreign particles and digest them. Sometimes, WBCs cannot digest bacteria or virus or foreign particles. Due to which they explode and die. If significant numbers of WBCs die, we suffer from different diseases. Leucocytes are produced by the stem cells in the red bone marrow and lymph nodes. They are destroyed in the liver, spleen and at a site of infection. There are about 4000-11000 WBCs in 1 mm3 of blood. Their life span is about two weeks or 15 days. In fact, the life span of WBC is not fixed as they may die anytime while fighting with the pathogens. WBCs are called the soldiers of our body, why? WBCs defend the body from disease causing agents. They kill or control the pathogens or foreign matterials. Therefore, WBCs are called the soldiers of our body. FACTS WITH REASON 1. The haemoglobin that carries oxygen is known as oxyhaemoglobin. 2. The haemoglobin that carries carbon dioxide is called deoxyhemoglobin. 3. Carboxyhemoglobin is the haemoglobin that carries carbonmonoxide (CO). CO is a poisonous gas. If CO binds with haemoglobin, one suffers from a condition known as carbon monoxide poisoning. MEMORY TIPS Neutrophil Eosinophil Lymphocyte Monocyte Basophil White blood cells WBCs are the largest blood cells with nucleus, whereas platelets are the smallest without nucleus. MEMORY TIPS WBCs have irregular shaped nucleus. The collection of dead WBCs, tissues, cells or other chemicals inside the tissues or skin is called pus. MEMORY TIPS

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 117 ACTIVITY 1 To observe blood clotting and blood film under the microscope 1. Wash your hands with soap and water. 2. Take a clean and sterilized lancet and prick your finger to extract few drops of blood. 3. Keep few drops of blood in a petri dish and observe the time taken for the blood clotting. 4. Similarly, keep few drops of blood in a slide, spread it using another slide uniformly and leave it to dry. 5. Add some Leishman stain on the blood sample. Then, observe the blood cells under a compound microscope. Platelets or Thrombocytes Platelets are non-nucleated, irregular, colourless, round or oval blood cells found freely suspended in the blood plasma. They are non-nucleated and irregular structures. They help in the blood-clotting in case of cuts and wounds. So, they prevent the loss of blood. In 1 mm3 of blood, there are about 2 to 4 lakh of platelets. Their life span is 2 to 3 days. They are produced in bone marrow and destroyed in spleen. Some blood disorders Anaemia Anaemia is a condition which is caused due to the lack of RBCs or haemoglobin in the blood. A person suffering from anaemia has pale eyes, face and nails. He/she feels tired even walking a short distance. It is because the blood cannot nourish the muscles with enough oxygen due to the lack of RBCs or haemoglobin. The person suffering from anaemia has following symptoms. i. Loss in weight ii. Loss in appetite iii. Pale eyes, face and nails iv. Feels tired even walking a short distance v. Slow and retard growth Haemophilia The fibrinogen (it is a type of protein) helps in the blood-clotting with the help of clotting factors. If these chemicals are not produced in the body, the process of blood-clotting delays. It is called haemophilia. Thus, haemophilia is a condition in which blood-clotting delays in the cuts and wounds due to the absence of blood-clotting chemicals. It is a sex-linked disease because it generally affects males. The females are the carriers of this disease i.e. they transfer this disease to the future generation. Haemophilia in females is very rare. Leukaemia Leukaemia is a condition in which a person has excess number of WBCs in their body. It is also called blood cancer. It is caused due to the excess production of abnormal WBCs that cannot be regulated by the body. Platelets If number of RBCs are more than range, it is called polycythemia. MEMORY TIPS Person suffering from haemophilia does not show blood clotting. As a result, continuous bleeding occurs form the cuts and wounds. MEMORY TIPS

118 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Leukopenia Leukopenia is a condition in which a person has reduced number of WBCs in their body. It makes a person susceptible to diseases. A person suffering from anaemia feels tired on walking a short distance, why? The circulatory system of the anaemic person cannot transport sufficient amount of oxygen to his/her muscles due to the lack of red blood cells or haemoglobin. As a result, muscle cells cannot release sufficient amount of energy for continuous walking. Hence, a person suffering from anaemia feels tired on walking a short distance. FACTS WITH REASON A summary of the comparison among RBC, WBC and platelets Feature RBC WBC Platelets Shape Biconcave Irregular Oval or round Size 7 µ 8-15 µ 2.5 µ Life span 90-120 days Few hours to 15 days 2-3 days Site of production Bone marrow Bone marrow and Lymph nodes Giant cells of bone marrow and mostly in lungs Site of destruction Liver and spleen Liver, spleen and site of infection Spleen Colour Red White colourless Types × 1. Granulocytes, e.g. neutrophils, eosinophils and basophils 2. Agranulocytes, e.g. lymphocytes and monocytes × Presence of Haemoglobin (Hb) and Nucleus Non- nucleated Hb present Nucleated Hb Absent Non-nucleated Hb absent Average number Females 4.5- 5 millions/ mm3 Males 5-5.5 millions/ mm3 6000-10000/ mm3 in both male and female 2-4 lakhs/ mm3 Function Transport O2 and CO2 Produce antibodies and fight against pathogens Helps in the clotting of blood Blood disorders caused by excess or deficiency of blood corpuscles Excess polycythaemia leukaemia or blood cancer Thrombocytosis Deficiency Anaemia Leukopenia Thrombocytopenia Clotting of Blood When there are cut, wound or tissue damage in the body, the platelets activate themselves and form a thick jelly-like mesh at the sites of cuts and wounds. As a result, bleeding stops. Thus, the process of formation of solid mesh at the site of cuts and wounds is called blood clotting or blood coagulation. Clotting prevents the further loss of blood from the cut and wound. In general, the duration of blood-clotting is about 4 to 10 minutes.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 119 There are dozens of blood-clotting factors and chemicals that take part during blood-clotting process. Blood-clotting does not occur inside the blood vessels because there are a number of anticoagulant proteins in the blood. For example, heparin. The blood-clotting should only occur when there is cut and wound in the body. Otherwise blood supply would cut off in the organs. As soon as there is injury in the blood vessel, the underlying collagen tissues are exposed to the platelets. These platelets bind with collagen tissues making aggregation at the site of wound. With the help of several chemical reactions and clotting factors, prothrombin is converted into thrombin. Similarly, thrombin converts fibrinogen to fibrin and forms a solid mesh-like structure. The solid mesh gathers more platelets and RBCs. As a result, a stable clot is formed. Functions of Blood The basic function of the blood is to transport gases (oxygen and carbon dioxide), nutrients and waste materials to the desired locations. But, the blood performs variety of other functions which are mentioned below: a) Transportation Blood transports essential materials like water, nutrients, hormones and oxygen to the tissues. It also transports waste substances like urea, carbon dioxide, etc. to the site of excretion. b) Protection Blood fights against germs and toxic materials. As a result, it protects body from various diseases. Platelets help in blood-clotting and prevent from loss of blood. c) Regulation Blood maintains body temperature. It regulates the amount of water in the body. It regulates different chemicals like salt, sodium, potassium, calcium, acidity, alkalinity, etc. Heart The heart is the centre of the circulatory system. It is cone-shaped hollow muscular organ. The size of the heart is approximately the size of the fist of owner. It measures about 12 cm in length and 9 cm in breadth. The average weight of the heart is about 300 grams in adults. The detailed structure of the heart can be studied in two headings. They are: External morphology of heart The heart is a three-dimensional conical muscular organ that contracts and relaxes rhythmically. Its morphology can be best Aorta Pulmonary artery Pulmonary veins Left auricle Left ventricle Pericardium Inferior vena cava Right ventricle Right auricle Pulmonary veins Superior vena cava External morphology of heart

120 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur studied by having either a model or an actual heart from a dead animal. It is a pumping organ of the body that makes the blood flow through the arteries. It is located between two lungs, in the centre of the chest. The two-third part of the heart is located towards the left. Heart is covered by a double-layered membrane. The double layered membranous structure that covers the heart is called pericardium. The two layers of the pericardium are close to each other forming a gap called pericardial cavity. The pericardial cavity contains a fluid in it. The lubricating fluid present in the pericardial cavity is called the pericardial fluid. Following are the functions of the pericardial fluid: i. It makes the heart beat smooth. ii. It also prevents the heart from the mechanical shock. The heart has hair-like blood vessels seen externally. These blood vessels are called coronary blood vessels. They carry blood towards and away from its own tissues. Coronary blood vessels are of two types. They are coronary artery and coronary vein. Coronary arteries carry oxygenated blood to the heart tissues and coronary veins collect deoxygenated blood to the heart. Internal morphology or anatomy of the heart The heart is a four chambered organ. The upper two chambers are called auricles and the lower two chambers are called ventricles. The two auricles are separated from each other by a septum called inter-auricular septum. Similarly, the two ventricles are separated from each other by a septum called inter-ventricular septum. Inside a normal heart, the blood flows only from the upper chamber to the lower chamber. That is, the auricles pump the blood to the ventricles. Then ventricles pump blood to lungs and other parts of the body at a high pressure. Thus, ventricles are more muscular than auricles. Among the two ventricles, left ventricle has to pump blood to all parts of the body at longer distance while the right ventricle has to pump the blood to the lungs at a shorter distance. Thus, the left ventricle is more muscular than the right ventricle. Heart has various blood vessels that end at it or start from it. There are mainly four apertures or passages in the heart that end or start in the four chambers. The four heart chambers and the blood vessels which attach to them are as follows: a) Right auricle The right auricle is the upper right chamber of the heart. It is responsible for collecting deoxygenated blood from all over the body. Altogether, three blood vessels end in the Superior vena cava Pulmonary artery Right auricle Aorta Pulmonary artery Pulmonary veins Left auricle Pulmonary valve Aortic valve Left ventricle Septum Cardiac muscle Pulmonary veins Tricuspid valve Right ventricle Inferior vena cava Bicuspid/mitral valve Internal morphology or anatomy of the heart

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 121 right atrium. They are superior venacava, inferior venacava and the coronary sinus. The superior venacava collects deoxygenated blood from the upper parts of the body like neck, brain etc. while the inferior venacava collects blood from the lower parts of the body like legs, liver, kidney, etc. The coronary sinus carries the deoxygenated blood from the heart muscles itself. All these blood vessels pour deoxygenated blood into the right atrium. The right auricle is bigger than the left auricle because it has to hold more volume of the deoxygenated blood collected from all over the body. b) Left auricle It is the upper left chamber of the heart. Two pairs of pulmonary veins, one pair from each lung are connected to the left auricle. They carry purified or oxygenated blood. c) Right ventricle It is the lower right chamber of the heart. Pulmonary artery arises from the right ventricle and is connected to the lungs. It carries deoxygenated blood from the heart to the lungs for purification. d) Left ventricle The left ventricle is the lower left chamber of the heart. It is the main pumping chamber. The largest artery called aorta arises from the left ventricle and carries the oxygenated blood away from the heart to all parts of the body. Why are ventricles more muscular? Auricles have to pump blood only to the ventricles. But, ventricles have to pump blood to the lungs and other parts of the body at a high pressure. So, ventricles are more muscular than auricles. Why is the left ventricle more muscular than the right ventricle? The left ventricle has to pump blood to all parts of the body at longer distance while the right ventricle has to pump the blood to the lungs at a shorter distance. So, the left ventricle is more muscular than the right ventricle. FACTS WITH REASON Differences between auricles and ventricles. S.N. Auricles S.N. Ventricles 1. Auricles are the upper two chambers of the heart. 1. Ventricles are the lower two chambers of the heart. 2. They are relatively thin-walled. 2. They are relatively thick-walled. 3. Auricles receive blood from inferior venacava, superior venacava, coronary sinus and pulmonary veins. 3. Ventricles receive blood from the auricles. 4. Auricles open into ventricles. 4. Ventricles open into arteries. 5. Auricles pump blood to the to ventricles. 5. Ventricles pump blood to the lungs and all parts of the body.

122 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Valves in the heart For one-way flow of the blood, there are four valves present inside the heart. A short description of these valves is given below. a) Tricuspid valve The valve between the right auricle and right ventricle is called tricuspid valve (tricuspid means three flaps). It is also called right auriculoventricular valve. When auricle contracts, tricuspid valve opens. At the same time the ventricle relaxes and blood flows from right auricle to the right ventricle. Similarly, when auricle relaxes, the tricuspid valve gets closed. At the same time, ventricle contracts and the blood flows from right ventricle to the pulmonary artery. b) Bicuspid valve or mitral valve The valve present between left auricle and the left ventricle is called bicuspid valve. It is also called the mitral valve. It is the only valve that has two concentric flaps. It is also called left auriculoventricular valve. When the left auricle contracts, bicuspid valve opens. At the same time, ventricle relaxes and blood flows from the left auricle to the left ventricle. Similarly, when right auricle relaxes, bicuspid valve gets closed. At the same time, ventricle contracts and the blood flows from the left ventricle to the aorta. c) Pulmonary valve The valve present between pulmonary artery and right ventricle is known as pulmonary valve. It has three concentric flaps. This valve opens when the auricle relaxes and ventricle contracts. As a result, blood flows from right ventricle to the pulmonary artery. d) Aortic valve The valve present between aorta and the left ventricle is known as the aortic valve. It also has three concentric flaps. This valve opens when auricle relaxes and ventricle contracts. As a result, blood flows from left ventricle to the aorta. The tricuspid and bicuspid valves are collectively called auriculoventricular valves, as they lie between auricle and ventricle. Similarly, the pulmonary valve and aortic valve are called semilunar valves because they look like half-moon. There is a valve in aorta but no any valve in the pulmonary vein. The four valves in the heart maintain unidirectional flow of blood by preventing the backward flow. The auriculoventricular valves allow unidirectional flow of blood from auricle to the ventricles. Similarly, the semilunar valves allow unidirectional flow of the blood from ventricles to the aorta and pulmonary artery. When ventricles contract, the auriculoventricular valves close and the semilunar valves open. Similarly, when ventricles relax, the auriculoventricular valves open and the semilunar valves close. In a normal healthy person, the flow of blood in the heart is always unidirectional. It flows Tricuspic valve Posterior Anterior Bicuspic valve Pulmonary valve Aortic valve Right side of heart Left side of heart Valves in the heart

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 123 from right auricle → right ventricle → pulmonary arteries → lungs → pulmonary veins → left auricle → left ventricle → aorta → body parts. The blood circulation is maintained by the pumping action of the heart. Blood Vessels The elastic tubes and pipes through which blood flows are called blood vessels. Blood vessels vary in shape, size, diameter and functions. Some blood vessels carry oxygenated blood while others carry deoxygenated blood. On the basis of structure and function, there are three types of blood vessels. They are: Arteries Arteries are thick-walled blood vessels that carry blood away from the heart. They start from the left ventricle of the heart as aorta i.e. the largest artery and then branch out. They carry oxygenated blood (except pulmonary artery which arises from right ventricle and carries deoxygenated blood). The wall of artery is made up of three layers. They are tunica interna (the innermost layer), tunica media (the middle layer, also the thickest) and the tunica externa (the outer layer). Arteries have thick wall to overcome high pressure. It is because the blood flowing in the arteries is directly pumped from the heart at a high pressure. They have a narrow lumen which maintains pressure to flow blood. No valves are present in the arteries because there is no chance of back flow of blood. Arteries branch out to form arterioles which further branch out to form capillaries. They are usually deep-seated in the body. It is because the loss of blood from the arteries is very dangerous during cuts and wounds as blood oozes out at a high pressure and clotting becomes difficult. Why are arteries thick walled? Arteries are thick walled to overcome the high pressure and high speed of the oxygenated blood which is directly pumped by the heart. Why do arteries have narrower lumen? Arteries have narrower lumen to increase the blood pressure. This sufficient blood pressure helps to transport blood to the different parts of the body. Pulmonary artery carries deoxygenated blood but is still called an artery, why? Pulmonary artery carries deoxygenated blood but is still called an artery because artery is a blood vessel that carries blood away from the heart. Pulmonary artery also carries the blood away from the heart to the lungs. Therefore, it is still called an artery even it carries deoxygenated blood. FACTS WITH REASON Tunica externa Tunica media Tunica interna Arteries

124 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Why do arteries have no valves? Arteries have no valves because valves prevent the backflow of the blood but there is no chance of back flow of blood in arteries as heart directly pumps the blood into the arteries at higher pressure. Blood loss from the arteries is dangerous. Give reason. Blood loss from the arteries is dangerous because: i) Arteries carry oxygenated blood and loss of oxygenated blood causes death of cells in the vital organs. ii) It is difficult for an artery to form blood clots after it is punctured. Why is the arterial blood not drawn during normal blood donation? Arterial blood is not drawn during blood donations because: i) Loss of arterial blood directly hampers the amount of oxygenated blood supply to the vital organs. ii) The deoxygenated blood transfused to the recipient is easily oxygenated by the lungs. FACTS WITH REASON Veins Veins are the thin-walled blood vessels that carry deoxygenated blood towards the heart (except pulmonary vein which carries oxygenated blood from lungs to the left auricle). Veins start from the different parts of the body as venules. These venules are formed by the union of many capillaries. All the veins of the body finally unite to form either superior venacava or inferior venacava. These large veins (venacava) pour blood into the right auricle. Like arteries, veins also have three layers in their walls, viz. tunica interna (innermost), tunica media (middle) and tunica externa (outer, thickest layer). They have a wider lumen than arteries through which deoxygenated blood flows easily at low speed and under low pressure. Veins have semilunar valves in them that allow one-way flow of blood. In veins, blood flows against gravity at low pressure. So, the valves at regular intervals prevent the back flow of the blood. Only three large veins of the body, viz. superior venacava, inferior venacava and the pulmonary veins do not have valves in them. Veins are superficial in position. They can be seen easily from outside. They cannot bear high pressure. Why are veins thin-walled? In veins, blood flows at low speed and under low pressure. Due to which extra thickness in the wall of the veins is not necessary. Veins have wider lumen, why? Veins have wider lumen to flow the large volume of the deoxygenated blood at low speed and under low pressure. Why do veins have valves at regular intervals? In veins, deoxygenated blood flows at low speed and under low pressure. From the lower parts of the body blood also flows against the gravity. In these conditions, there may be chance of back flow of the blood. Hence, to prevent the back flow of the blood, veins are provided with valves at regular intervals. FACTS WITH REASON Tunica externa Valve Tunica media Tunica interna Veins

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 125 Why is blood seen as blue or purple from outside the veins? Veins are superficial. They have thin walls and transport deoxygenated blood. The wall of veins and deoxygenated blood absorb all the colours of light except blue. So, due to reflection of blue light, we see blood vessel blue or purple. Pulmonary vein carries oxygenated blood but it is still called a vein, why? Vein is a blood vessel that carries blood towards the heart. Pulmonary vein also carries blood towards the heart. Therefore, it is still called a vein even though it carries oxygenated blood. FACTS WITH REASON Capillaries Capillaries are hair-like, extremely narrow and thin-walled blood vessels. They are present everywhere in the body. Half of the capillaries transport oxygenated blood to the body while other half collect deoxygenated blood from there. They are the connection between arterioles and venules. They are microscopic with one cell layer thick. They are the actual site of the exchange of nutrients, toxic waste and gases (O2 and CO2 ). The wall of capillaries has only one layer. It is called tunica interna. Tunica externa and tunica media are absent. Presence of only one layer in the wall of capillaries supports them to reach up to the microscopic cellular level. Tunica interna Artery Arteriole Capillary network Venule Vein Capillaries Differences between arteries and veins. S.N. Arteries S.N. Veins 1. Arteries carry blood away from the heart to the tissues. 1. Veins carry blood towards the heart from the tissues. 2. The blood in arteries flows at high pressure and under high speed. 2. The blood in veins flows at low speed and under low pressure. 3. They do not have valves (except in aorta). 3. They have valves (except in superior venacava, inferior venacava and pulmonary vein). 4. They usually carry oxygenated blood except pulmonary artery. 4. They usually carry deoxygenated blood except pulmonary vein. 5. They are located deep in the tissues. 5. They are located superficially in the tissues. 6. They have narrow lumen. 6. They have wider lumen.

126 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Why are capillaries extremely thin-walled? Capillaries are extremely thin-walled because the thin wall allows the capillaries to exchange oxygen, carbon dioxide, nutrients, toxic waste, etc. in the cellular level. FACTS WITH REASON Blood circulation The heart of the vertebrates (except Pisces) follows the double circulation because the blood flows through the heart twice to flow the oxygenated blood once in the body. The deoxygenated blood from all over the body pours into the right auricle and then right ventricle of the heart. From right ventricle, the blood enters into the lungs. After oxygenation, the pure blood enters into the left auricle and then left ventricle to distribute throughout the body. A healthy heart pumps about 5-6 litres of blood every minute. The double circulation of the blood occurs through two ways. The blood circulation in human is called double circulation, why? In human blood circulatory system, the blood is transported to the heart twice: once from all parts of the body and second from the lungs. So, the blood circulation in human is called double circulation. FACTS WITH REASON Pulmonary circulation The type of circulation in which blood flows from right ventricle to the lungs and then to the left auricle is called pulmonary circulation. Pulmonary circulation starts from the right ventricle and pumps deoxygenated blood to the lungs through the pulmonary artery. In the lungs, the blood becomes oxygenated by exchanging carbon dioxide with oxygen. This process is called blood purification. After oxygenation, the lungs transport oxygenated blood through the pulmonary veins back to the left auricle. Systemic circulation The circulation of blood from the left ventricle to the right auricle of the heart through body tissues (except lungs) is called systemic circulation. Systemic circulation starts from the left ventricle. When the left ventricle contracts, the oxygenated blood passes to the aorta, arteries, arterioles and Pulmonary circulation Systemic circulation Pulmonary circulation and systemic circulation

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 127 finally to the capillaries. In the tissues, the capillaries exchange nutrition, oxygen, hormones, with metabolic wastes of the tissues like carbon dioxide, toxic materials, etc. Now, the blood becomes impure. This impure blood passes to the venules, veins, venacavae and finally to the right auricle of the heart. This is a complete systemic circulation. Blood group A blood group is a classification of blood, based on the presence or absence of antigens present in RBCs and antibodies in blood plasma. These antigens are designated by the English alphabets A and B and antibodies as a and b. Depending upon the presence and absence of these antigens and antibodies, four blood groups have been designated as A, B, AB and O. This system of blood grouping is called as ABO blood grouping system. FACTS WITH REASONS Some people used to die and some people used to survive after blood transfusion before the blood group was discovered. Some people used to die and some people used to survive after blood transfusion before the blood group was discovered because of the transfusion of the wrong blood group. Transfusion of wrong blood group is dangerous. The antigen of the opposite blood group will destroy the red blood cells and kills the patient. ACTIVITY 2 Let’s survey the blood groups of our classmates. ABO blood grouping system 1. If a person’s blood has antigen A in the RBC and antibody b in the plasma, the person has blood group A. 2. If a person’s blood has antigen B in the RBC and antibody a in the plasma, the person has blood group B. 3. If a person’s blood has antigens A and B in the RBC and no antibody in the plasma, the person has blood group AB. 4. If a person’s blood has no antigen in the RBC but both antibodies and b in the plasma, the person have blood group O. Blood group Antigen in RBC Antibody in plasma A A b(anti B) B B a (anti-A) AB A and B None O None a and b (Anti-A and anti-B) The blood groups A, B and O were discovered by Karl Landsteiner in 1900 for which he got Nobel Prize in 1931. MEMORY TIPS

128 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Rh-Factor Rh-factor (Rhesus factor) is a protein (antigen) that is present on the surface of RBC. If Rh factor is present in a person’s blood, then blood is said to be Rh positive (Rh+) and if Rh factor is absent, then blood is said to be Rh negative (Rh–). Project Work Ask to your elders and neighbour about their blood group. Make a list of their blood group and present in the class. FACTS WITH REASONS A person with blood group A should not transfuse blood group B. Immune system of person with blood group A will produce antibodies against blood group B antigens and destroy them resulting loss of blood cells. So, person with blood group A should not transfuse blood from person with blood group B. Determination of Blood group 1. First of all, a finger is sterilized with a sterile cotton ball and pricked with a sterile blood lancet. 2. Three drops of blood are taken in different places on glass slides for A, B and Rh-Factor (D). 3. The anti A serum is added in the drop of blood labelled A, anti B serum is added in the drop of blood labelled B and Anti D serum is added in the drop of blood labelled D, respectively. 4. The mixture of blood and antiserum is mixed properly with the help of a bamboo stick and allow resting for a few minutes to see agglutination (clumping). 5. If we see clumping in blood labelled A after putting anti-serum-A, then its blood group is A. 6. Similarly, if we see clumping in blood labelled B after putting anti-serum-B, then its blood group is B. 7. If we see clumping in both A and B, then the blood group is AB. 8. If we see no clumping in both A and B, then the blood group is O. 9. Similarly, agglutination of sample D indicates the Rh+. 10. If there is no clumping of a sample D, then the blood is Rh-. Lets put figure something like this, which can explain blood determination visually Rh-Factor was first isolated from RBCs of Rhesus Monkey by Karl Landsteiner and Wiener in 1940. MEMORY TIPS

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 129 Importance of blood group in blood donation When it comes to blood donations, it is important to know about the different types of blood group. If patient gets blood that does not match to his blood group, patient immune system could attack the donated blood. There may occur intravenous blood clotting. This can lead to a dangerous or even life-threatening transfusion reaction. ACTIVITY 3 What is your blood group? If you do not know, ask your parents to take you hospital for a blood test. Blood Pressure (BP) The pressure exerted by blood on the walls of the arteries when the left ventricle contracts and relaxes is known as blood pressure. When the blood pumped by the left ventricle runs through the arteries, it creates a pressure against the wall of the arteries. This pressure is measured in the mercury column. Hence, the unit of blood pressure is millimetres of mercury (mmHg). It is represented by two numbers. The upper level number is called systolic blood pressure and the lower one is called diastolic blood pressure. Systolic blood pressure Systolic blood pressure is the measure of maximum pressure in the arteries when left ventricle contracts. The contraction of heart is also called as systole. In adults, systolic blood pressure ranges from 90-130 mm of Hg. The normal systolic blood pressure is considered 120 mm of Hg. Diastolic blood pressure Diastolic blood pressure is the measure of minimum pressure in the arteries when left ventricle relaxes. The relaxation of heart is called diastole. In adults, the diastolic blood pressure ranges between 60-90 mmHg. The normal diastolic blood pressure is considered 80 mmHg. The blood pressure of a person changes with the factors like age, sex, time of the day, stress, exercise, work, emotions, disease, fear, etc. Sphygmomanometer is the device that measures blood pressure. A sphygmomanometer and stethoscope are used to measure blood pressure manually. A trained person can measure the correct blood pressure by using such an analog sphygmomanometer. But a digital sphygmomanometer is easy to operate without training. It can be used in noisy environments too. If the blood pressure increases above the value 140/90 mmHg, it is called high blood pressure. Similarly, if it drops below 90/60 mm of Hg, it is called low blood pressure. High blood pressure (Hypertension) High blood pressure is a condition in which the heart pumps blood at high pressure against the wall of arteries. High Analog sphygmomanometer Digital sphygmomanometer If the blood pressure of a person is 120/80 mm of Hg, it means that the systolic blood pressure is 120 mm of Hg and the diastolic pressure is 80 mm of Hg. These values of blood pressure are within the normal limit. MEMORY TIPS

130 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur blood pressure increases the risk of heart attack, kidney damage, cardiovascular stroke, nerve damage around blood vessels, etc. High blood pressure cannot be treated fully but with the change in life style, it can be kept in control. It is necessary to keep the blood pressure under control to avoid the risk of death by heart attack, brain haemorrhage, kidney damage, etc. Symptoms of high blood pressure The normal blood pressure is about 120/80 mmHg for majority of people. The blood pressure reading greater than or equal to 140/90 is called hypertension. Often people experience following symptoms due to high blood pressure. i. Headache ii. Shortness of breath iii. Nose bleeding iv. Heart tremors v. Nervousness and sweating vi. Facial reddening vii. Difficulty in sleeping viii. Anxiety ix. Nausea x. Dizziness or blurred vision It is found that, most people feel no symptoms at all. So, one has to regularly monitor his/her blood pressure even if they feel completely normal. If possible, home blood pressure monitor should be bought and regular monitoring should be done at home. If not measured and not controlled in time, high blood pressure can cause heart attack, brain haemorrhage, kidney damage, etc. without any warning symptoms. Causes of high blood pressure Most of the causes of high blood pressure are idiopathic (not known). But, there are some causes which increase the chances of hypertension. They are: i. Ageing (age more than 40 years) ii. Over weight iii. Family history of high blood pressure (heredity) iv. Excessive salt intake in diet v. Excessive smoking and drinking alcohol vi. Lack of physical exercise vii. Kidney, thyroid and adrenal diseases viii. Diabetes ix. Women using birth control pills x. Stressful living xi. Pregnancy Preventive and control measures of high blood pressure High blood pressure cannot be fully treated. But, with some changes in lifestyle, the blood pressure can be kept under safer limit. Some of the ways to reduce the risk of high blood pressure are: i. We should reduce weight if our weight is above the limit. ii. We should do regular physical exercises. iii. We should eat low salt and low sugar.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 131 iv. We should avoid smoking and drinking alcohol. v. We should eat balanced diet. vi. We should avoid fatty, oily, and spicy foods. vii. We should reduce stress and avoid stressful living. viii. We should avoid the consumption of fatty red meat. ix. We should monitor blood pressure regularly. Heart Beat If you hold a stethoscope close to the chest, you will hear the repetitive lubb-dup sound of the heart. It goes somewhat this way: lubb-dub—lubb-dub—lubb-dub…. The lubb sound (first heart sound, S1) represents the contraction of the ventricles and the relaxation of the auricles. Likewise, the dub sound (second heart sound, S2) indicates the relaxation of the ventricles and contraction of the auricles. But, the heart sounds are actually produced by the closing of the heart valves. The closing of the mitral and the tricuspid valves produces the first heart sound (lubb sound S1), whereas the closing of the pulmonary and the aortic valves produces the second heart sound (dub sound S2). A heart beat is a continuous rhythmic beat throughout the life which is produced due to complete contraction and relaxation of the heart muscle. A normal healthy person has 60-72 times heart beats in one minute. The heart beat over 100 is known as tachycardia while the heart beat below 60 is known as bradycardia. Arterial pulse The repetitive jerk felt at the major arteries of the body due to the pumping action of the heart is known as the arterial pulse. In a normal healthy person, the arterial pulse is equal to the heart beat i.e. 60-100 times per minute. The major arteries where the pulse can be felt are radial artery (wrist), common carotid artery (neck), temporal artery (temporal lobe of head), etc. Diabetes We need energy to work. The required energy is derived from the metabolism of food that we eat. Our food mainly contains carbohydrates, proteins and fats. They are broken down into simpler molecules like glucose and amino acids. Most of our energy is derived from glucose. Except brain, liver and testes, most of the cells require a hormone called insulin for the better use of glucose in the body. Insulin is a hormone secreted by pancreas that helps in glucose utilization. Thus, insulin helps to remove excess glucose present in the blood by utilizing in the cells. Lack of insulin causes high level of glucose in the blood. The condition of high level of glucose in the blood is called hyperglycaemia. If the function of insulin is affected or the cells of pancreas are damaged, the ability of the body to remove excess glucose from temporary artery facial artery carotid artery femoral artery Brachial artery Radial artery Popliteal artery Posterior tibial artery dorsalis pedis artery Major superficial pulse points

132 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur the blood is reduced. This condition is called diabetes. Thus, the condition in which body becomes unable to maintain normal glucose level due to the lack of insulin is called diabetes mellitus. It is also called sugar disease. A random glucose test can be done at home too by a portable device called glucometer. The normal range of glucose in blood for a healthy person is from 80-110 mg/dl (milligrams/decilitre). MEMORY TIPS a) Diabetes mellitus Diabetes mellitus is a condition in which the body fails to remove extra glucose from the blood. This extra glucose gets accumulated in the blood and is passed through urine. In this diabetes, the pancreas either does not produce insulin or there is a resistance to the action of insulin. It is the most common diabetes in the people of our country. b) Gestational diabetes (GD) The diabetes which occurs due to low insulin production or due to insulin resistance during the pregnancy is known as gestational diabetes. It occurs in the middle or late pregnancy. But, it may completely disappear after pregnancy. Causes of diabetes i. Diabetes is caused due to the damage of insulin producing cells of pancreas. ii. It is caused due to insulin resistance. iii. Obesity and inactive lifestyle may cause diabetes. iv. Unbalanced diet with more fats and carbohydrates may cause diabetes. v. Aging is also responsible for diabetes. vi. Heredity also may cause diabetes. Symptoms of diabetes i. Excessive urination ii. Intense thirst and hunger iii. Unexplained weight gain or loss iv. Perspiration v. Presence of sugar in urine vi. Syncope (Unconsciousness) vii. Blurred vision viii. Slow healing of wounds ix. Tiredness x. Muscle cramping Preventive measures of diabetes Diabetes cannot be cured completely, but can be effectively controlled. With an appropriate change in lifestyle, one can prevent it (except if it is genetic). Some preventive measures of diabetes are: i. We should reduce obesity. ii. We should reduce inactive lifestyle.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 133 iii. We should do regular jogging, walking or regular physical exercises. iv. We should eat balanced diet which is rich in green vegetables and fruits. v. We should eat food having low carbohydrates. vi. We should maintain stress free life. vii. We should avoid smoking and drinking alcohol. Diabetes may be caused by inactive lifestyle, why? Due to the lack of exercise, the extra glucose is stored in the body and is not used up. This stored glucose in the body increases the body weight and thus the level of glucose in the blood may not be maintained properly. It finally leads to diabetes. People should monitor their blood pressure regularly, why? People should monitor their blood pressure regularly to detect the increase or decrease in the pressure beyond normal values. Both high blood pressure and low blood pressure are dangerous. If we monitor blood pressure regularly, we can prevent various cardiovascular diseases. We should eat a lot of fruits and vegetables, why? We should eat a lot of fruits and vegetables because they provide us vitamins and minerals which help to fight against diseases, prevent high blood pressure, diabetes, etc. and remove toxic substances from the body. FACTS WITH REASON Gout or Uric acid Uric acid is a compound which is produced by the breakdown of an organic compound called purine. Purines are nitrogenous compounds that help to make DNA, RNA and proteins in the human body. The sources of purines are liver, kidneys and brains of animals, beans, alcoholic beverages, mushroom, sea foods, red meat, tomatoes, eggs, etc. Purine is also produced by the breakdown of cells in the body. It is believed that uric acid is an antioxidant which helps to remove toxic materials from our body and also protects the inner walls of the blood vessels. Foods rich in purines may cause uric acid. The high concentration of uric acid is harmful to our body. The normal level of uric acid in blood is 3.4-7.2 mg/dL (milligrams/ decilitre). The condition in which there is excess of uric acid in the body is called hyperuricemia. Generally, the high level of uric acid in blood is prevented due to its excretion by the kidneys through urine. If kidneys fail to excrete enough uric acid, it gets precipitated and deposited in the soft tissues and large joints of the body. This causes gout. Gout is a form of arthritic disease which is characterized by the deposition of uric acid crystals in the large joints of body like knee, toe etc. Normally, uric acid is removed by the kidneys. But, when the level of uric acid is high, it starts getting precipitated. This process is similar to sugar crystallization. Risk factors of gout include alcohol use, obesity, high purine diet, use of certain medicines, etc. Project Work Ask to your elders and neighbours about the condition of their blood pressure and uric acid. Make a list and present in the class. Purine is broken down into uric acid by liver and intestinal mucosa. MEMORY TIPS

134 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Causes of uric acid (Gout) i. Uric acid is caused due to kidneys fail to excrete it through urine. ii. It can be caused due to different kidney disease, kidney failure, etc. iii. It can be caused due to high metabolic rate of purines in the body. Symptoms and effects of uric acid (Gout) i. Increased concentration of uric acid in the body ii. Joint and muscle pain due to the deposition of urate crystals iii. Pain in joints early in the morning. A painful big toe joint (i.e. gout of the big toe) is called podagra. iv. Difficulty in walking and movement v. Swelling, burning and tenderness in joints vi. Reddish or purple skin Preventive and control measures of uric acid (gout) i. We should reduce weight through physical exercise. ii. We should drink adequate water at regular intervals. iii. We should eat foods like cherries which contains antioxidant called anthocyanin. iv. We should avoid drinking alcohol. v. We should eat baking soda or its products. vi. We should avoid red meat (mutton, pork, etc.), legumes and sea-food. vii. We should eat low purine diet. Eating a lot of cherries is beneficial for health, why? Cherries contain an antioxidant called anthocyanin. It removes the harmful free substances from the body and prevents uric acid deposition in blood. Aging people should consume less salt, carbohydrates and proteins, why? Aging people should consume less salt, carbohydrates and proteins to prevent, or control the diseases like high blood pressure, diabetes and uric acid. FACTS WITH REASON Heart attack The heart is a blood-pumping organ. It is made of cardiac muscles. It needs a continuous supply of oxygen-rich blood. The coronary artery supplies pure blood to the cardiac tissues of the heart. Sometimes certain things block the flow of oxygen-rich blood to the heart. As a result, the cardiac tissue starts to die. The blockage of the flow of pure blood into the cardiac tissues of the heart is called a heart attack. If the blood flow is blocked for a longer time, more damage is sustained by the heart. A heart attack is also called a myocardial infarction. It is a life-threatening condition. It must be treated within two hours to increase the survival rate. If a large portion of the heart is damaged by a heart attack, then the heart stops beating followed by death. It is called cardiac arrest. Before it is too late, we should be able to notice if it is a heart attack or not. Then we can follow the curative methods to save lives. A healthy lifestyle helps to reduce the chances of a heart attack. Swollen and inflamed joint uric acid crystals Podagra Heart attack from the use of cocaine is one of the most common causes of sudden death in young people. MEMORY TIPS

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 135 We should avoid sedentary life. We should avoid sedentary life to prevent diabetes, obesity and heart attack. FACTS WITH REASONS ACTIVITY 4 Explain the risks and preventive measures of heart attack to your parents. Symptoms of a heart attack i. Chest pain, discomfort in jaw, neck or back. ii. Discomfort in one or both shoulders. iii. Short of breath followed by chest pain. iv. Feeling dizzy or fainting. Causes of heart attack i. Smoking and drinking alcohol can cause coronary heart diseases (CHD). The CHD can start a heart attack. ii. Diabetes, high cholesterol and high blood pressure can damage the coronary artery and cause a heart attack. iii. Obesity can lead to a heart attack. iv. Lack of oxygen in the blood can start a heart attack. Carbon monoxide poisoning can cause a heart attack because it removes oxygen from the blood. v. Use of drugs can constrict the coronary arteries. As a result, blood cannot flow properly into the heart and the heart tissues start to die. Preventive measures As we discussed above heart attack is fatal. It is caused by our lifestyle. We must improve our lifestyle to prevent heart attacks. Some common ways to prevent heart attack are discussed below. i. Avoid drinking too much alcohol because it can cause obesity and irregular heartbeat. ii. We must learn to handle stress because a high level of stress can cause coronary heart disease which leads to a heart attack. iii. Quitting smoking significantly reduces the chances of a heart attack. iv. Eat a healthy balanced diet. Especially low on fat, salt and spices. Consume more vegetables, grains and low-fat dairy products. v. Do physical exercises regularly. Smoking can cause a heart attack. Smoking can cause a heart attack because nicotine increases blood pressure which is one of the risk factorsfor heart attack. FACTS WITH REASONS MEMORY TIPS Low-impact activities such as walking, swimming and cycling are recommended to reduce probability of a heart attack.

136 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur ACTIVITY 5 Practise following the preventive measures for heart attack every day. Live a healthy life. Diagnosis and curative measures of heart attack Heart attack can be diagnosed by checking blood pressure, blood test, electrocardiogram, chest x-ray, echocardiogram, angiogram and Cardiac CT scan. If we have symptoms of heart attack doctors will start treatment. During emergencies, it's wise to call for help, stop driving, chew an aspirin, stay calm and lie down. Coughing, putting pressure on heart and panicking will worsen the case. In hospitals,curative health service is provided to the patients as soon as the heart attack is confirmed. The main objective of the curative health service is to restore the blood supply to the heart. The two main ways to restore blood flow are angiography and bypass surgery. Angiography Angiography is an effective way to treat a heart attack. It uses an x-ray imaging technique to find the blood clot. It can take half an hour to one hour time to perform angiography. The patients are administered a mild sedative. Doctors clean the part in arm and punch a tiny hole. A catheter is inserted through an artery. A catheter is a thin hollow tube. Then it is moved up to the heart. X-ray images help doctors to know the location of the catheter. A special dye is passed through the catheter and multiple X-ray images are taken continuously to observe the flow of dye through the artery. The dye will highlight the blood clot or any other disturbance in blood flow. When the blood clot is found, doctors will put a metallic mesh tube (stent) where the artery is narrow or blocked. It will resupply the blood to the heart tissues. First of all, they push a tiny balloon through the blockage that removes the blood clot. Then, they put stent so that artery won't close again. Angiography is generally a safe procedure. It does not hurt but we can feel the catheter being moved in the artery. A thin metallic tube is inserted through the blockage during angiography. A thin metallic tube is inserted through the blockage during angiography because it helps to pass blood through the blockage into the heart. FACTS WITH REASONS There are various types of angiography based on the organ that is being looked at. Angiography is used to look at kidneys, lungs etc. too. MEMORY TIPS Figure: Angiography

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 137 Bypass surgery Bypass surgery means finding alternative arteries to supply blood to the cardiac tissue of the heart when the majority of blood vessels are blocked or are very narrow. The narrowing of the coronary artery is called coronary artery disease. The blood cannot reach heart tissues through narrow arteries. It may cause a heart attack. If many coronary arteries are blocked and oxygen is not supplied enough into the heart the doctors will suggest bypass surgery. The objective of bypass surgery is to find a healthy artery that supplies blood to hand or chest or find a healthy saphenous vein from thighs. And use it to supply fresh blood to the heart. Its one end is connected to the aorta that supplies pure blood and another end is connected to the coronary artery beyond the blockage. One or many bypasses are made at a time based on the number of narrow coronary arteries. To perform bypass surgery doctors cuts the sternum bone in half length wise. They push each piece sideways to see the heart. Then the doctors will connect a heart-lung bypass machine to the heart to pump blood. The heart itself is stopped for a certain duration during the surgery. The bypass surgery is performed only during an emergency as a last option. It can sometimes cause pneumonia, kidney failure, blood loss and even death. Many bypasses are made during single surgery if many coronary arteries are narrow. If many coronary arteries are narrow, there will be a shortage of oxygen in the heart that can cause heart attack again. So, doctors make many bypasses to supply more pure blood into the heart. FACTS WITH REASONS ACTIVITY 6 Make a 3D model to show the concept of multiple (2) bypass surgery. Cardiac rehabilitation Cardiac rehabilitation is a promotive health service. It includes exercise, support, counseling etc. to get heart patient get better. It can last for 2 to 8 months. Coronary artery bypass grafting (CABG) is used to treat heart attacks. Many coronary arteries can be bypassed in a single surgery. MEMORY TIPS Figure: Coronary bypass surgery

138 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur HOT SKILL HIGHER ORDER THINKING SKILL 1. Circulatory system, respiratory system and digestive system are interrelated. The respiratory system is responsible for absorbing oxygen from the lungs and giving it to the cells. The digestive system is responsible for converting food into nutrients. The circulatory system is responsible for absorbing nutrients from the intestine and gives to the cell. Only then mitochondria of the cell use oxygen and nutrients to produce energy through respiration. Hence respiratory system, digestive system and circulatory system work together to produce energy for our body and remove waste. 2. Mr. Anurema once survived a heart attack. Doctors performed balloon angiography on him to save his life. Mention the lifestyle should he live from now onwards. Mr. Anurema once survived a heart attack because doctors performed angiography on him. Therefore, he must practice cardiac rehabilitation and live a healthy life. For example: i. He should avoid drinking alcohol. ii. He should not stress over small issues. He should learn ways to handle stress. iii. He should quit smoking to reduce his blood pressure. iv. He should eat a healthy balanced diet. Especially low on fat, salt and spices. v. He should consume more vegetables, grains and low-fat dairy products. vi. He should do physical exercises regularly. 3. Arya’s father is suffering from excessive thirst, excessive hunger, frequent urination, unconsciousness and blurry vision. What disease is he suffering from? She is worried that it could be hereditary and that she could develop it. How should she live to avoid it? If Arya’s father is suffering from excessive thirst, excessive hunger, frequent urination, unconsciousness and blurry vision, then he may be suffering from diabetes. Yes, it is true that, if our father and mother have diabetes, we are likely to get diabetes ourselves. So, Arya should be very careful and live in following way: i. She should do regular physical exercise, reduce obesity and eat freshly prepared foods. ii. She should consume low-carbohydrates food. iii. She should decrease the consumption of processed foods, quit smoking and quit alcohol. iv. She should consume a few cups of sugarless tea and coffee because they are rich in antioxidants. 4. Study the table and answer the following questions: Person Wounds Blood leakage A Deep cut Faster blood leakage rate, stopped only after first aid B Minor cut Slower blood leakage rate, stopped naturally C Minor cut Slower blood leakage rate, did not stopped after first aid i. Why did not blood clot in person C? The blood did not clot in person C, because he is suffering from haemophilia. ii. Why did blood leak faster in person A? The blood leaked faster in person A because it was a deep cut in arteries. The blood flows with high pressure in the artery so it is difficult to prevent blood loss with minor first aid. iii. Which person’s life is at threat among A and B? Why? Among persons A and B, the life of person A is at threat. It is because person A has a deep cut in the artery. The blood flows faster with high pressure. Lots of blood could be lost and the person can faint or die.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 139 5. What is the cause of systolic pressure in arteries when the left ventricle contracts? The cause of systolic pressure in arteries when the left ventricle contracts is the flow of pressurised blood into the arteries due to contraction. The fast-flowing pressurised blood pushes the wall of arteries and produces greater pressure. 6. If a person has chest pain and is brought to the hospital, what kind of test should be prioritized? If a person has chest pain and is brought to the hospital, then the tests that can detect heart attack and coronary blockage should be prioritized. 7. Can cell and tissues get nutrients to survive if there is no circulatory system? The cells and tissues cannot get nutrients to survive if there is no circulatory system because it is responsible for absorbing nutrients from the intestine and transporting it to the cell. 8. Why is blood red? Blood is red because there are millions of RBCs in every drop of blood and each RBC has an ironcontaining red pigment called haemoglobin. 9. Whenever grandfather eats red meat, fried grams, peanuts and cold beer, his joint hurts and swells. What is the disease he is suffering from? What should we be aware of if we want to avoid such a problem? What kind of consequences will he suffer if he continues the same lifestyle? If the grandfather suffers from joint pain and swelling if he consumes red meat, peanut or alcohol, the most probable diseases is high uric acid and gout. If he wants to avoid uric acid and gout, he should change his life style. For example: i. He should walk, trot or do physical exercises a lot. ii. He should drink plenty of water. iii. He should eat healthy fruits and green vegetables. iv. He should reduce the consumption of red meat, legumes, alcohol or any food rich in protein. He will suffer from the following consequences if he continues the same lifestyle: i. He will suffer from permanent bone, tissue and joint damage. ii. Uric acid can damage kidneys. iii. Uric acid can cause heart disease. iv. Long-term gout can cause eye cataracts and dry eyes. 10. A person has a light headache, sweating, anxiety and a blood pressure of 145/95. Which disease do these symptoms refer to? How can one minimize or control his/her symptoms without medications? Modern lifestyles are responsible for diabetes, uric acid and blood pressure, etc. Justify the statement. The above symptoms refer to high blood pressure. One can minimize or control his/her symptoms by changing his/her lifestyle. Taking a diet with low fats, carbohydrates, proteins, less salt, daily exercise, stress control, etc. are some of the ways to control high blood pressure. If these continuous efforts do not lower blood pressure, one should follow medications. Nowadays, facilities are easily accessible. People do very less physical work. They do maximum work by using different kinds of machines. They want to live luxurious life using modern equipment. Not only these, but farmers also became more commercial. They use different kinds of chemical fertilizers, insecticides, pesticides, etc. to increase the production of crops, vegetables and fruits. Consumption of these food products and a passive lifestyle are responsible for diabetes, uric acid and blood pressure.

140 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur 3 STEPS 3 STEPS EXERCISE EXERCISE STEP1 1. Choose the best answer from the given alternatives. a. Which one is not the function of plasma? i. coagulation of blood ii. regulate body temperature iii. transportation of hormones iv. absorption of oxygen from lungs b. What is phagocytosis? i. process of producing antibodies ii. process of producing heparin iii. process of engulfing germs iv. process of coagulating blood c. What does it mean by artery? i. blood vessel that starts from auricles ii. blood vessel in which pure blood flow iii. blood vessel in which impure blood flow iv. blood vessels that start from ventricles d. What happens if blood group A is put in a person whose blood group is B? i. it can save a life because RBC will start to supply energy. ii. anti A in patients’ blood will kill blood group A iii. the blood group will lose antibodies because of the presence of blood groups A and B. iv. their blood group will change e. What is shown in the diagram? i. heart bypass surgery ii. angiography iii. uric acid iv. vein and the valve f. Which one is the first aid if a person is unconscious due to heart attack? i. angiography ii. heart bypass surgery iii. ultrasonography iv. CPR 2. Define the following terms with the required examples. a. Circulatory system b. Blood c. Red Blood Corpuscles d. White Blood Corpuscles e. Platelets f. Anaemia g. Haemophilia h. Leukopenia i. Leukaemia j. Coagulation k. Blood pressure l. Systolic blood pressure m. Diastolic blood pressure n. Arterial pulse o. Pulmonary circulation p. Systemic circulation

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 141 q. Diabetes r. Gout (uric acid) s. Heart attack t. Cardiac arrest u. Angiography v. Heart bypass surgery 3. Answer the following questions in very short. a. Write the percentage composition of plasma and blood corpuscles. b. Mention the name of pigment present on the surface of RBC. c. Name the largest artery and vein in the human body. d. Which blood vessels have valves in them? e. What antigens are present in blood group A? f. Where is the pericardial fluid located? g. Mention the disease caused by the lack of insulin in the blood. h. State the meaning of double circulation. i. Mention the value of normal blood pressure in an adult. j. Where do platelets form and destroy? k. What does hypertension mean? l. Name the device that measures blood pressure. m. What antibody is in the plasma if the blood group of that person is A positive? n. Which artery has impure blood? o. Which muscular tissue makes the heart? p. Which vein is harvested by doctors for bypass surgery? q. What is passed through the catheter to make blood visible? r. What makes the blood red? s. Which chemical produces uric acid upon digestion? t. Which hormone reduces the concentration of glucose in the blood? u. A person has pain in the chest that is slowly rising to the jaws. What could be the most probable cause? v. What is the first aid for a heart attack when the patient is unconscious? w. What happens if the RBC count is too low in the body? x. Which disease is caused by a lack of haemoglobin? y. How many chambers are there in the heart? Write their names. z. How many valves are there in the human heart? Write their names. STEP2 4. Give reasons a. Blood is red. b. WBCs are called soldiers of our body. c. Arteries are thick-walled. d. Veins are thin-walled. e. Arteries have no valves on them.

142 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur f. Veins have valves on them but arteries do not. g. Ventricles are more muscular than auricles. h. The left ventricle is more muscular than the right ventricle. i. Veins lie just below the skin but arteries are placed deep inside the muscles. j. Blood group must be identified before blood transfusion. k. An anaemic person feels tired while walking a short distance. l. Eating a lot of cherries is beneficial to health. m. A healthy artery from the chest is attached to the heart during bypass surgery. n. Consumption of fatty food, smoking and drinking alcohol should be reduced. o. Pulmonary artery has a valve. p. Dye is passed through the catheter during angiography. q. Healthy lifestyle can reduce the probability of heart attack. 5. Differentiate between the following. a. RBC and WBC b. Red blood cells and platelets c. Auricles and ventricles d. Artery and vein e. Systolic blood pressure and diastolic blood pressure f. Anaemia and leukaemia g. Pulmonary artery and pulmonary vein h. Pulmonary artery and aorta i. Angiography and bypass surgery j. aorta and pulmonary artery 6. Answer the following questions in short. a. We must live a physically active life to remain healthy. Justify. b. How do blood clots naturally at wounds after a few minutes? What is the cause of difficulty in blood clots? c. Patients with uric acid experience pain in the joints. How joints become painful? d. A person has a BP value of 120/80 mmHg. What does it mean? e. Draw a well-labelled diagram of the external morphology of the heart. f. What are the preventive measures for heart attacks? g. Some people can experience symptoms of a heart attack but some cannot. Enlist some of the common symptoms of a heart attack. h. What are the three major causes of a heart attack? What kind of activities usually lead to a heart attack? i. From where and which blood vessel is harvested for bypass surgery? j. Which blood cell is amoebic and which blood cell do not have nucleus?

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 143 7. Answer the following questions on the basis of the table given below. i. Which procedure to treat a heart attack is shown in the diagram? ii. Write the name of A. Where is it harvested from? iii. What is B? Where is it harvested from? iv. What is the objective of blood vessel A? STEP3 8. Answer the following questions. a. Describe the circulatory system in brief by explaining the role of each organ. b. Compare arteries and veins based on wall size, function and presence of valves. c. What kind of symptoms can be observed if a person has a low WBC count? d. Write the causes, symptoms and controlling measures of high blood pressure. e. Write the causes, symptoms and controlling measures of diabetes. f. Write the causes, symptoms and controlling measures of uric acid. g. Write down the main functions of: i. Blood ii. Lymph iii. RBCs iv. WBCs v. Platelets vi. Pericardial fluid vii. Aortic valve viii. Aortic valve ix. Pulmonary valve x. Mitral valve xi. Tricuspid valve h. ‘There is a high risk of diabetes, uric acid and blood pressure in people with an inactive lifestyle.’ Justify the statement. i. How can hypertension be prevented or controlled? Can it be cured completely? Write reasons to support your statement. j. Explain the internal structure of the heart with the help of a diagram. k. Describe blood circulation in the human body. l. What do you mean by angiography? How does angiography save us from cardiac arrest? Clarify. How is it performed? m. What is heart bypass surgery? How is it done? n. What kind of lifestyle should we adopt to reduce the probability of heart attack? o. Mr. Krishna Bahadur has suffered from gout. What lifestyle is better for him to avoid the consequences of having gout? p. Study the given table and answer the following. Blood cells Shape Nucleus A Biconcave Absent B Irregular Present C Round Absent i. Write the name of A, B and C. ii. Low count of which blood cells cause anaemia?

144 PHySiological StRuctuRe and life PRoceS S Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur iii. Which disease a person suffers from if B is more in number? iv. Which blood cell is lacking if blood does not clot efficiently in the wounds? 9. Answer the following questions on the basis of the given diagram. a. Name the parts A, B, C and D that are shown in the diagram and write their life span. b. Identify the figures (a) and (b) and write any two differences between them. (a) (b) c. Look at the diagram alongside and answer the following questions: i. What happens if valve B opens and closes? ii. What happens if valve D opens and closes? iii. Among the four valves, which two valves open and close at the same time? iv. When do you hear a heartbeat during this process? v. Where does the blood go from valve A? d. Study the given flow chart and answer the following: left ventricle > body > right auricle i. What type of blood circulation is it? ii. Which blood vessels take blood from the left ventricle to the body? iii. Which blood vessels take blood from the body to the right auricle? A B C D A C D E

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 145 Key terms and terminologies of the unit 1. Climate : Climate is an average weather condition recorded over a long period of time (usually 30 years). 2. Climate change : Climate change is a regular or irregular alteration in the weather patterns observed over a very long period of time. 3. Endangered animals : Animals or birds whose distribution are limited and are few in number at a given geographical area at that time are called endangered animals. 4. Endangered plants : Plants whose distribution are limited and are few in number at a given geographical area at that time are called endangered plants. 5. Medicinal plants : Medicinal plants can be defined as the plants that possess therapeutic properties or exert beneficial pharmacological effect on the human or animal body. 6. In situ conservation : The conservation of animals and plants by maintaining them in their natural ecosystem in which they occur is called in situ conservation. 7. Ex situ conservation : The conservation of animals and plants outside the natural ecosystem like zoo, botanical garden, zoological park, seed bank, etc. is called ex situ conservation. Climate Climate is an average weather condition recorded over a long period of time (usually 30 years). It is obtained by collecting the statistical data of temperature, precipitation, seasons, humidity etc. for a long period of time in a place. It is different from weather as weather is a temporary condition e.g. rainy, windy, cloudy or sunny. Sequence of Curriculum Issued by CDC  Concept of climate change: cause, effects and control measures  Different kinds of endangered animals in Nepal and their conservation  Importance, identification and uses of medicinal plants UNIT Nature and Environment 6 Estimated teaching period Theory Practical 5 2 Sir Arthur George Tansley is known as a pioneer in the science of ecology. He was born in England on 15th August 1871 and died on 25th November 1955. He is a botanist and ecologist. He introduced the concept of the ecosystem in biology. He was honoured with the Linnean Medal and a Fellow of the Royal Society. He was educated at Highgate School, University College London and Trinity College, Cambridge. Sir A. G.Tansley About the Scientist

146 natuRe and enviRonment Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Climate Change Climate of a place doesn’t change much even during many decades or it is difficult to notice the change. Due to this slight change, the average temperature of the earth’s surface remains constant. Thus it supports life on the earth. If the earth’s temperature increases even slightly e.g. by 2 degree Celsius, then it will be disastrous. If we study the climate data since 1880 A.D., it has been found that the change in climate has accelerated. The surface temperature has risen by 1.80 F. It is a bad news. It is to be noted that climate continuously changes due to natural causes like solar activity, earthquake, volcano, earth’s rotation etc. But change due to natural cause is very slight. The main problem is anthropogenic causes (human causes). Scientists believe that the greenhouse gases, environmental pollution, deforestation, industrial gases and other human activities are the main reasons behind the change in climate. Now, let us define climate change. Climate change is a regular or irregular alteration in the weather patterns observed over a very long period of time. To observe climate change, we need to analyze the statistical data of decades. Causes of Climate change A. Natural causes of climate change The different types of natural phenomenon like volcano, evaporation, emission of green house gases, etc. are responsible for climate change. 1. Change in solar activity There occurs thermonuclear fusion reaction in the sun. It produces solar energy. If there is change in the rate of thermonuclear fusion reaction, it changes production of solar energy. As a result, it changes climate of the earth. 2. Change in the reflection of the sun light The reflection of the sunlight depends upon the surface of the earth and its atmosphere. About 70% of the solar radiation is absorbed by the earth surface. This absorbed solar radiation increases the heat of the earth. This heat changes climate of the earth. 3. Volcanic activities Volcanic eruption brings out tremendous amount of carbon dioxide, sulphur dioxide, water vapour, ashes and dust particles. These substances released in the atmosphere produce various other compounds that surround the earth’s atmosphere. If these substances are carried by equatorial winds, they will prevent the heating effect and thus cause cooling of climate.