67 Label the following Match the words below with the correct definition. (a) The breakdown of food from large complex molecules (i) assimilation To smaller simpler substances (b)The diffusion of digested food into the blood (ii) digestion (c) The act of taking food into the mouth (iii) egestion (d) The release of undigested wasted via the anus (iv) absorption (e) The distribution and usage of digested food by the body (v) ingestion
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69 Unit 7: Respiration & Gaseous Exchange
70 Respiration is the process by which the food is burnt to produce energy. Since oxygen is used in the reaction it is called aerobic respiration. The process is catalyzed by enzymes and is also called cellular, internal or tissue respiration. How do food and oxygen get to respiring cells? A respiring cell needs both food (glucose) and oxygen. Food: in animals, food eaten is digested and absorbed into the bloodstream. The end-products of digestion eventually reach all the body cells. In plants, the food made in photosynthesis in the leaves travels around in phloem tubes and eventually reaches all body cells. Oxygen: Oxygen comes from the air that is inhaled into the lungs. It diffuses into the bloodstream and is transported to all the body cells. In plants, some of the oxygen comes from photosynthesis and some diffuse in through the leaves and other parts of the plant. Products and waste product of aerobic respiration In both plants and animals, the type of food from which energy is released is usually glucose. Energy is released when glucose combines with oxygen. Carbon dioxide is a waste product of this reaction. In vertebrates, carbon dioxide diffuses back into the bloodstream, to be taken to the lungs and exhaled out of the body. In plants, it is used for photosynthesis during daylight. How does aerobic respiration occur? Respiration occurs in a series of steps, each of which is catalyzed by enzymes. The overall process ca n be summarized in words or by the equation below. During aerobic respiration, glucose is completely broken down into carbon dioxide and water. At each step in the breakdown of glucose, energy is released. This is used to convert a chemical called adenosine di phosphate (ADP) into adenosine triphosphate (ATP). Each molecule of ATP acts as a little ‘packet’ of energy. The energy can be stored and used later when needed. Some advantages of storing and using energy in small packets like this: The energy can be released from ATP wherever and whenever it is required by a cell The energy can be released rapidly The energy can be used to drive numerous chemical reactions quickly
71 Energy can be stored as ATP in one part of a cell and transported to another place without causing reactions in between Energy is not wasted. A large amount of energy is released by oxidizing one glucose molecule and many ATP molecules are formed. A cell may require very much energy at once. By storing the energy in ATP molecules, the cell can use small amounts of energy as required. Where does aerobic respiration occur? Aerobic Respiration occurs in the mitochondria of cells. Mitochondria are referred to as the powerhouses of cells and are present in all cells, animal and plant. The energy stored in ATP is released when it is converted back to ADP. Anaerobic respiration Anaerobic Respiration is respiration that occurs in the absence of oxygen. Both aerobic and anaerobic respiration involve the breakdown of glucose. However, in anaerobic respiration, it is not completely broken down. Aerobic Respiration Anaerobic respiration requires oxygen Does not require oxygen In plants and animals: C6H12O6 + 6CO2 ENERGY + 6 H20 + 6 CO2 Water and carbon dioxide are waste products In animals cells: C6H12O6 ENERGY + 2 C3H6O3 Lactic acid is the waste product In plant cells: C6H12O6 ENERGY +2 C2H5OH + 2CO2 ethanol and carbon dioxide are waste products Large amounts of energy produced (2880) kJ) per glucose molecule Small amounts of energy are produced (150 KJ) per glucose molecule in animals and (210 KJ) in plants Glucose is broken down completely to inorganic molecules Glucose is not broken down completely – ethanol and lactic acid are organic molecules that still contain useful energy Occurs in the mitochondria of cells Occurs in cytoplasm of cells Habitats such as stagnant ponds and deep underground have no oxygen. Organisms living there have adapted to survive without oxygen, they must respire anaerobically all the time. These organisms include some worms,
72 some bacteria and some fungi. Parasites that live inside other organisms, such as the gut parasite tapeworm and bacteria, also live in conditions that lack oxygen. They must also respire anaerobically. Many living cells that normally respire aerobically can also respire anaerobically if oxygen is lacking. Animal and plant cells do this in different ways. Anaerobic respiration in humans Human cells normally respire aerobically. However, during strenuous exercise muscle cells need much more energy for extra work that they are doing. The heart rate and breathing rate increase in an attempt to get more oxygen to these cells. Sweating also occurs to help lose some of the extra energy as heat. With increased respiration, a lot of heat is produced which is lost from the skin. After a period of sustained exercise, the oxygen supply becomes inadequate, even with panting for air and the increased heart rate. The muscle cells then respire anaerobically. Energy is still produced when cells respire anaerobically, although it is a much smaller amount for each molecule of glucose. This means that they can continue to do work. Lactic acid is a waste product of this reaction. It builds up in the muscles and causes them to ache. This is often called fatigue. After exercise the body has to get rid of the lactic acid as quickly as possible. This is done by using oxygen to change it back to a chemical like glucose so that it can be broken down completely in aerobic respiration. When anaerobic respiration occurs in muscles it is in addition to aerobic respiration and not in place of it. A person continues to breathe hard or pant for some time after exercise because oxygen is needed to get rid of the lactic acid. The oxygen required to get rid of the lactic acid is called the oxygen debt. Anaerobic respiration in bacteria Some bacteria also respire anaerobically. Like animal cells, they make lactic acid as a waste product. We make use of this in the manufacture of yoghurt and cheese. Anaerobic respiration in yeast During anaerobic respiration in yeast, ethanol and carbon dioxide are produced as waste products. Ethanol is an alcohol and the process is known as alcoholic fermentation. Yeast is very important in the making of alcohol and bread. The ethanol can be produced in many ways to make a wide range of alcoholic drinks, including beer and wine, which are enjoyed by humans. The production of carbon dioxide is used in bread-making to make the dough rise. The carbon dioxide produced by the yeast as it respires, accumulates inside the dough in small pockets. The dough rises as the gas expands with warmth. The ethanol that is produced evaporates as the bread is baking.
73 Class work
74 Assignment 1A
75 Class work 1B
76 Gaseous Exchange. Importance of gaseous exchange in humans Respiring cells need a constant supply of oxygen. They must also be able to get rid of the carbon dioxide that is being produced continuously. The blood is the means by which oxygen and carbon dioxide are transported to and from cells. At some point, blood has to pick up oxygen and give off carbon dioxide, that is, exchange these two gases. In humans, gaseous exchange takes place in the lungs. Mechanism of gaseous exchange in Humans the human respiratory system is involved in the exchange of gases in humans. The lungs are very important and are made up of many tiny air spaces or air sacs called alveoli. Air first enters the nose and or mouth, the nose contains hair and mucus which helps to trap dirt and dust particles and prevent them from entering the trachea. The air then moves down the trachea (windpipe). the trachea is supported by C-shaped rings of cartilage so that it is kept open at all times. The trachea then divides into two bronchi, the right and left bronchi. These are also supported by rings of cartilage. Each bronchus branches into smaller and smaller tubes called bronchioles. At the end of each bronchiole are the many tiny air sacs called alveoli. Gaseous exchange occurs in the alveoli. Objectives: Students will be able to: Understand the function and mechanism of breathing and gaseous exchange in humans Describe the structure and function of the respiratory system in man Identify characteristics common to gaseous exchange surfaces Discuss the effects of cigarette smoking in humans Source: https://www.biologydiscussion.com/
77 The walls of the alveoli are the gaseous exchange surfaces or the respiratory surfaces. The smallest blood vessels, capillaries, are closely wrapped around each alveolus. Blood is thus brought to and taken away from the alveolus. Oxygen diffuses across the walls of the alveolus into the capillary and the blood in the capillary becomes oxygenated. Carbon dioxide diffuses from the capillary into the alveolus and is exhaled out of the body. The walls of the alveolus and capillary are very thin (only one cell across) so that diffusion can occur readily. The continuous exchange of gases in the lungs is very important. Body cells can obtain a constant supply of oxygen for respiration and the carbon dioxide that is constantly being produced is exhaled out of the body. Gaseous exchange also occurs at the cellular level. Here oxygen leaves the blood and diffuses into the cells. Carbon dioxide moves in the opposite direction. The trachea is lined with mucus, a slimy substance which traps and holds dust and microorganisms. The trachea is also lined with microscopic hair-like extensions called cilia. These beat in a wave like manner, moving the mucus containing dust and microorganisms out of the lungs. Pathogens can enter the lungs with air as it is breathed in. The mucus and cilia afford some protection by trapping and moving them out of the lungs. If an irritating substance like dust is breathed in, this can stimulate a sneeze during which the irritant is ejected out of the lungs. The other parts of the respiratory system, namely the ribs, intercostal muscles and diaphragm, are also involved in gaseous exchange. They help to move air in and out of the lungs. Breathing in is called inspiration and breathing out is called expiration.
78 Table 1: Table showing the difference between inhaled and exhaled air. Gas Inspired Air % Expired Air % Explanation Nitrogen 79 79 Cannot be used in the body in that form Oxygen 21 16 Used up in respiration Carbon dioxide 0.04 4 Produced in respiration Water vapour variable saturated Produced in respiration Moisture evaporates from surface of alveoli The mechanism of Breathing in humans Inhalation Exhalation External intercostal muscles contract, internal intercostal relax, and the ribcage is raised. The internal intercostal muscles contract, external intercostal relax, and the rib cage is lowered. The muscles of the diaphragm contract and the diaphragm moves downwards The diaphragm relaxes and the diaphragm moves upwards. The two movements increases the volume of the thorax These two movements decrease the volume of the thorax. The pressure inside the thorax decreases , this pushes air into the lungs so they expand The pressure inside the thorax increases which squeezes the lungs. Air rushes into the lungs though the mouth nose and trachea. Air is pushed out of the lungs, it passes through the trachea and the mouth or nose out of the body.
79 Characteristics of gaseous exchange surfaces. Gaseous exchange surfaces are those surfaces where gases are exchanged. These surfaces must have certain characteristics that encourage: A lot of gaseous exchange to take place Gaseous exchange to take place quickly Gaseous exchange to take place continuously. This ensures that oxygen is readily available and CO2 is constantly being removed. Adaptations for efficient gaseous exchange Large Surface Area: more surfaces for gaseous exchange to occur (alveoli, lamellae, leaves, cell membrane of amoeba) Thin for gaseous exchange: allows diffusion of gases to occur quickly Constantly moving transport medium: for gaseous exchange to take place continuously. The medium which brings the gases must be constantly moving so the concentration gradient is maintained Cigarette Smoking and the Respiratory System Tobacco may be the cause of over 3 million deaths a year, worldwide. Death from cigarette smoking comes mainly from lung cancer, but heart disease is also associated with smoking. The products of cigarette smoke include tar, nicotine and carbon monoxide. However, there are many other harmful components in cigarettes. Nicotine Makes cigarettes addictive Reduces air flow into and out of lungs Paralyses the cilia lining the trachea so they cannot remove dirt and bacteria Raises blood pressure Raises heart rate Increases the risk of osteoporosisthis makes bones brittle and they break more easily and are more difficult to heal. Tar Sticks to cells in the lungs Causes the development of cancer Damages lung tissue, causes “smokers cough” Breaks down alveoli thus decreasing the surface area for gaseous exchange Causes bronchitis or inflammation of lining of air passages Source: http://wackyy.blogspot.com/
80 Carbon Monoxide Combines irreversibly with RBC Causes less oxygen to be transported by blood Reduces smokers ability to take strenuous exercise Causes breathlessness Can be passed from mother to foetus where it affects the growing baby. Marijuana This is a green or grey mix of dried shredded flowers and leaves of the help plant Cannabis sativa. Also called by many other names including pot, spliff, herb, ganja and weed. The active ingredient is THC tetrahydrocannabinol which provides the ‘high’ that users experience when they smoke the drug. The short term effects can include: Problems with memory and learning Distorted perception Difficulty thinking Difficulty problem solving Loss of coordination Increased heart rate Anxiety and panic attacks Hallucinations Marijuana smoke is unfiltered users inhale more deeply and hold the smoke in the lungs. The effects on the lungs are thus greater than those caused by tobacco smoke because more tar and more carbon monoxide are inhaled. Disorders that affect the respiratory system Asthma Emphysema Cystic fibrosis Cancer Bronchitis Pneumonia Covid-19
81 Assignment 1B
82 Class work 1C
83 Assignment 1C Across 3. component of cigarettes that make it addictive 5. these are tubes that branch off from the trachea, they lead in to smaller tubes called bronchioles. 9. product produced when bacteria respires anaerobically to produce lactic acid 11. component of cigarettes that reduces the amount of oxygen that is carried by the blood 15. the process by which food is burnt to produce energy 17. respiration that occurs in the absence of oxygen 18. substance produced when humans respire anaerobically 20. common respiratory disorder characterised by difficulty breathing, wheezing, coughing. Down 1. respiration that occurs in the presence of oxygen 2. in order for respiration to occur living cells require oxygen and _______. 4. hair like structures found in the trachea that helps to remove dirt and microorganisms 6. gas which is a waste product of cellular aerobic respiration 7. component of cigarette smoke that sticks to the cells in the lung and damages lung tissue, it is also responsible for the development of lung cancer 8. site for anaerobic respiration 10. process where by yeast cells respire anaerobically to produce ethanol and carbon dioxide 12. site for aerobic respiration 13. ring of muscle that contracts and relaxes to move up and down thereby controlling the breathing process 14. the extra oxygen needed by the body to get rid of lactic acid produced during anaerobic respiration 16. gaseous exchange surface in humans
84 Assignment 1D
85 References 1. New Integrated Science for Caribbean Schools Book 1 and 2 Biology for CSEC References Biology for CSEC, M. Karen, Korby, P and Madhosingh L, 2nd edition, Nelson Thornes https://www.lexico.com/en/definition/ https://www.bioexplorer.net/divisions_of_biology/ https://creakyjoints.org/wp-content/uploads/0619_Tuberculosis-and-Arthritis.jpg https://www.123rf.com/photo_92647421_stock-vector-streptococcus-pyogenes-icon-cartoon-illu stration-of-streptococcus-pyogenes-vector-icon-for-web-.html http://venndiagramr.lesmonnaieschampenoises.fr/diagram/diagram-of-binary-fission-in-amoeba https://www.alamy.es/imagenes/hidra-invertebrados.html https://www.quora.com/What-are-some-examples-of-unicellular-organism https://png.pngtree.com/png-clipart/20190516/original/pngtree-mushroom-cartoon-cartoon-mushroom-lovelypng-image_3921237.jpg https://science4fun.info/wp-content/uploads/2017/05/flowering-plant.jpg https://aminghori.blogspot.com/2016/03/lesson-plan-of-plants-flowering-non.html https://www.netclipart.com/isee/ixRbRo_drawing-lemon-fruit-tree-oak-plant-black-and/ https://www.canstockphoto.com/olive-baboon-walking-vector-45416423.html
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