GENERAL BIOLOGY 2 LAS QUATER 4

GENERAL BIOLOGY 2

NAME: ___________________________________ GRADE LEVEL: ____
SECTION: _________________________ DATE: __________

LEARNING ACTIVITY SHEET
MAINTAINING STEADY INTERNAL CONDITIONS

Background Information for the Learners (BIL)

The tendency to maintain a stable, relatively constant internal environment is
called homeostasis. The body maintains homeostasis for many factors in addition to
temperature. For instance, the concentration of various ions in your blood must be kept steady,
along with pH and the concentration of glucose. If these values get too high or low, you can
end up getting very sick.

Homeostasis is maintained at many levels, not just the level of the whole body as it is
for temperature. For instance, the stomach maintains a pH that's different from that of
surrounding organs, and each individual cell maintains ion concentrations different from those
of the surrounding fluid. Maintaining homeostasis at each level is key to maintaining the body's
overall function.

So, how is homeostasis maintained? Let's answer this question by looking at some
examples.

Maintaining homeostasis
Biological systems like those of your body are constantly being pushed away from their

balance points. For instance, when you exercise, your muscles increase heat production,
nudging your body temperature upward. Similarly, when you drink a glass of fruit juice, your
blood glucose goes up. Homeostasis depends on the ability of your body to detect and oppose
these changes.

Maintenance of homeostasis usually involves negative feedback loops. These loops
act to oppose the stimulus, or cue, that triggers them. For example, if your body temperature
is too high, a negative feedback loop will act to bring it back down towards the set point, or
target value, 98.60F or 37.0∘C.

How does this work? First, high temperature will be detected by sensors—primarily
nerve cells with endings in your skin and brain—and relayed to a temperature-
regulatory control center in your brain. The control center will process the information and
activate effectors—such as the sweat glands—whose job is to oppose the stimulus by bringing
body temperature down.

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Image credit: modified from Homeostasis: Figure 1 by OpenStax College, Anatomy & Physiology, CC BY 4.0

Of course, body temperature doesn't just swing above its target value—it can also drop
below this value. In general, homeostatic circuits usually involve at least two negative feedback
loops:
• one is activated when a parameter—like body temperature—is above the set point and is

designed to bring it back down.
• the other is activated when the parameter is below the set point and is designed to bring it

back up.
To make this idea more concrete, let's take a closer look at the opposing feedback loops
that control body temperature.
Homeostatic responses in temperature regulation

If you get either too hot or too cold, sensors in the periphery and the brain tell the
temperature regulation center of your brain—in a region called the hypothalamus—that your
temperature has strayed from its set point. For instance, if you’ve been exercising hard, your
body temperature can rise above its set point, and you’ll need to activate mechanisms that cool
you down. Blood flow to your skin increases to speed up heat loss into your surroundings, and
you might also start sweating so the evaporation of sweat from your skin can help you cool off.
Heavy breathing can also increase heat loss.

Image showing temperature regulation in response.
Image credit: Homeostasis: Figure 4 by OpenStax College, Biology, CC BY 4.0

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Disruptions to feedback disrupt homeostasis.
Homeostasis depends on negative feedback loops. So, anything that interferes with the

feedback mechanisms can—and usually will! —disrupt homeostasis. In the case of the human
body, this may lead to disease. Diabetes, for example, is a disease caused by a broken feedback
loop involving the hormone insulin. The broken feedback loop makes it difficult or impossible
for the body to bring high blood sugar down to a healthy level.

To appreciate how diabetes occurs, let's take a quick look at the basics of blood sugar
regulation. In a healthy person, blood sugar levels are controlled by two hormones: insulin and
glucagon. Insulin decreases the concentration of glucose in the blood. After you eat a meal,
your blood glucose levels rise, triggering the secretion of insulin from β cells in the pancreas.
Insulin acts as a signal that triggers cells of the body, such as fat and muscle cells, to take up
glucose for use as fuel. Insulin also causes glucose to be converted into glycogen—a storage
molecule—in the liver. Both processes pull sugar out of the blood, bringing blood sugar levels
down, reducing insulin secretion, and returning the whole system to homeostasis.

Image credit: modified from The endocrine pancreas: Figure 2 by OpenStax College, Anatomy & Physiology, CC BY 4.0

Glucagon does the opposite: it increases the concentration of glucose in the blood. If
you haven’t eaten for a while, your blood glucose levels fall, triggering the release of glucagon
from another group of pancreatic cells, the α cells. Glucagon acts on the liver, causing glycogen
to be broken down into glucose and released into the bloodstream, causing blood sugar levels
to go back up. This reduces glucagon secretion and brings the system back to homeostasis.

Diabetes happens when a person's pancreas can't make enough insulin, or when cells in
the body stop responding to insulin, or both. Under these conditions, body cells don't take up
glucose readily, so blood sugar levels remain high for a long period of time after a meal.
This is for two reasons:

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• Muscle and fat cells don't get enough glucose, or fuel. This can make people feel tired and even
cause muscle and fat tissues to waste away.

• High blood sugar causes symptoms like increased urination, thirst, and even dehydration.
Over time, it can lead to more serious complications.
Positive feedback loops
Homeostatic circuits usually involve negative feedback loops. The hallmark of a
negative feedback loop is that it counteracts a change, bringing the value of a parameter—such
as temperature or blood sugar—back towards it set point.
Some biological systems, however, use positive feedback loops. Unlike negative
feedback loops, positive feedback loops amplify the starting signal. Positive feedback loops
are usually found in processes that need to be pushed to completion, not when the status quo
needs to be maintained.
A positive feedback loop comes into play during childbirth. In childbirth, the baby's
head presses on the cervix—the bottom of the uterus, through which the baby must emerge—
and activates neurons to the brain. The neurons send a signal that leads to release of the
hormone oxytocin from the pituitary gland.
Oxytocin increases uterine contractions, and thus pressure on the cervix. This causes
the release of even more oxytocin and produces even stronger contractions. This positive
feedback loop continues until the baby is born.

Normal childbirth is driven by a positive feedback loop

Image credit: Homeostasis: Figure 2 by OpenStax College, Anatomy & Physiology, CC BY 4.0

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Osmotic Balance
Osmosis is the diffusion of water across a membrane in response to osmotic

pressure caused by an imbalance of molecules on either side of the
membrane. Osmoregulation is the process of maintenance of salt and water balance (osmotic
balance) across membranes within the body’s fluids, which are composed of water, plus
electrolytes and non-electrolytes. An electrolyte is a solute that dissociates into ions when
dissolved in water. A non-electrolyte, in contrast, doesn’t dissociate into ions during water
dissolution. Both electrolytes and non-electrolytes contribute to the osmotic balance. The
body’s fluids include blood plasma, the cytosol within cells, and interstitial fluid, the fluid that
exists in the spaces between cells and tissues of the body. The membranes of the body (such as
the pleural, serous, and cell membranes) are semi-permeable membranes. Semi-permeable
membranes are permeable (or permissive) to certain types of solutes and water. Solutions on
two sides of a semi-permeable membrane tend to equalize in solute concentration by movement
of solutes and/or water across the membrane.

As seen in figure 1.1. a cell placed in water tends to swell due to gain of water from the
hypotonic or “low salt” environment. A cell placed in a solution with higher salt concentration,
on the other hand, tends to make the membrane shrivel up due to loss of water into the
hypertonic or “high salt” environment. Isotonic cells have an equal concentration of solutes
inside and outside the cell; this equalizes the osmotic pressure on either side of the cell
membrane which is a semi-permeable membrane.

https://opentextbc.ca/biology/wp-content/uploads/sites/96/2015/03/Figure_41_01_01.jpg
Figure 1.1. Cells placed in a hypertonic environment tend to shrink due to loss of water. In a
hypotonic environment, cells tend to swell due to intake of water. The blood maintains an
isotonic environment so that cells neither shrink nor swell. (credit: Mariana Ruiz Villareal)

The body does not exist in isolation. There is a constant input of water and electrolytes
into the system. While osmoregulation is achieved across membranes within the body, excess
electrolytes and wastes are transported to the kidneys and excreted, helping to maintain osmotic
balance.

Why Are the Kidneys So Important?
Most people know that a major function of the kidneys is to remove waste products and

excess fluid from the body. These waste products and excess fluid are removed through the
urine. The production of urine involves highly complex steps of excretion and re-absorption.
This process is necessary to maintain a stable balance of body chemicals.

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The critical regulation of the body's salt, potassium and acid content is performed by
the kidneys. The kidneys also produce hormones that affect the function of other organs. For
example, a hormone produced by the kidneys stimulates red blood cell production. Other
hormones produced by the kidneys help regulate blood pressure and control calcium
metabolism.
The kidneys are powerful chemical factories that perform the following functions:

• remove waste products from the body
• remove drugs from the body
• balance the body's fluids
• release hormones that regulate blood pressure
• produce an active form of vitamin D that promotes strong, healthy bones
• control the production of red blood cells

LEARNING COMPETENCY

Explain how some organisms maintain steady internal conditions.
(STEM_BIO11/12-IVi-j-2)

ACTIVITY NO. 1: FACT OR BLUFF?
Analyze each statement below. If the statement is correct write FACT and give your

reason. If it is incorrect, write BLUFF and underline the word/words that makes the statement
incorrect and write the correct answer on the line provided after the statement.

__________1. The tendency to maintain a stable, relatively constant internal environment is
called homeostasis. ____________________________________

__________2. Maintenance of homeostasis usually involves negative feedback loops.
____________________________________________

__________3. The normal body temperature of a human being is 98.8 0C.
____________________________________________

__________4. When an individual strenuously exercise, his body temperature can reach
below the set point. ____________________________________

__________5. Glucagon decreases the concentration of glucose in the blood.
______________________________________________

__________6. Diabetes happens when a person’s pancreas cannot make enough insulin.
______________________________________________

__________7. Positive feedback loop amplifies the starting signal.
______________________________________________

__________8. Oxytocin increases uterine contraction. _____________________________
__________9. The neurons send a signal that leads to release of the hormone oxytocin from

the pituitary gland. _________________________________________
__________10. The body maintains homeostasis for many factors in addition to temperature.

_____________________________________________________

Guide Questions:
1. What does homeostasis mean and how does it work?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

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2. Why is the endocrine system important in homeostasis?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

3. How does homeostatic disruption/imbalance affect the body? Cite an example of the
resultant complications that may occur.

___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

ACTIVITY NO. 2. FILL IN!
Study the diagram below. Label the corresponding box into an appropriate action.

Choose the answer from the box below.

Skin and brain sense change Rise in body temperature
Skin makes sweat and blood vessels dilate Command from the brain

How do hormones influence life’s processes?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

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ACTIVITY 3. LOGIC DIAGRAM
Compare and contrast Feedback loops using a Venn Diagram.

Positive Feedback Negative Feedback

Similarities
Feedback

Guide Questions:

1. A negative feedback loop causes a decrease in function; a positive feedback loop will
increase a function. It reinforces the change until the stimulus is removed. With these,
give two (2) concrete examples to explain these feedbacks.

___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

2. How can you relate negative feedback mechanism in your daily life activities? Give at
least one (1) and explain.

___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

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Activity No. 4. HOW IT WORKS?

A concerned individual regarding his/her health condition read about the maintenance
of blood glucose levels in the body and he/she presented to you a diagram, as shown below. As
endocrinologist, you are tasked to interpret the said diagram through an Infomercial/VLOG.

Image source: By Gabi Slizewska

Guide Questions:

1.What are the other Negative Feedback mechanisms in the body and how do they work?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

2. How do the endocrine and nervous systems work or interact to maintain homeostasis or
dynamic equilibrium in the body? Provide an example.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

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RUBRIC FOR SCORING (Infomercial/VLOG)

Criteria Awesome A Good Effort A Work in Just Beginning

Progress

5 43 2

Content- ◻ All contents are ◻ Most (90-99%) ◻ Many (75-89%) ◻ Fewer than 75%
Accuracy and correct, clear, of the contents of the contents of the contents
Clarity
relevant, and are correct, are are

informative. clear, relevant, correct, clear, correct, clear,
and informative. relevant, and relevant, and

informative. informative.

Citations ◻ Acknowledges all ◻ Acknowledges ◻ Acknowledges ◻ Does not
Presentation
images, media and most images, only few images, acknowledge

text with media and text media and text images, media

captions and with captions with captions and text with

created by others and created by created and does captions and

and displays others and not display created by

appropriate displays accurate and others and does

copyright appropriate properly not include

permissions and copyright formatted accurate and
permissions and citations.
accurate citations accurate citations. properly

formatted

citations.

◻ Shows confidence ◻ Shows some ◻ Unsure of ◻ Portrayal stalls
◻ Mumbles
◻ Speaks loudly confidence responsibility

and clearly ◻ Can be heard ◻ Hard to hear

Creativity and ◻ VLOG shows ◻ Infomercial ◻ Infomercial ◻ No creativity in
Originality
considerable shows some shows an attempt the production of

originality and originality and at originality and the VLOG.

inventiveness. inventiveness. inventiveness. ◻ Does not insert

◻ The content and ◻ The content and ◻ Selects and any graphics and

ideas are ideas are inserts low multimedia.

presented in a presented in an quality graphics

unique and interesting way. and multimedia

interesting way. ◻ Selects and that do not

◻ Selects and inserts inserts graphics enhance the

high quality and multimedia content.

graphics and that are mostly

multimedia to high quality and

enhance content’s enhance the

visual appeal and clarity of

increase content.

readability.

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Scientific ◻ Integrates several ◻ Integrates most ◻ Integrates few ◻ Does not
Thought
scientific thoughts scientific thoughts scientific thoughts Integrates
that helps or that helps or that helps or
promotes healthy promotes healthy promotes healthy scientific
lifestyle.
lifestyle. thoughts that

lifestyle. helps or

promotes healthy

lifestyle.

REFLECTION

I learned that __________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

I enjoyed most on ______________________________________________________
___________________________________________________________________________
___________________________________________________________________________

I want to learn more on __________________________________________________
___________________________________________________________________________
___________________________________________________________________________

REFERENCES FOR LEARNERS

https://www.webmd.com/diabetes/how-sugar-affects-diabetes
https://www.healthline.com/health/thermoregulation
https://flexbooks.ck12.org/cbook/ck-12-middle-school-life-science-

2.0/section/1.8/primary/lesson/characteristics-of-life-ms-
Ramos-Morales, Anna Cherylle and Ramos, John Donnie, Exploring Life Through Science,General

Biology 2, pp.123-128

https://www.expii.com/t/maintain-internal-environment-characteristics-of-life-10035

https://brainly.ph/question/2534278

https://opentextbc.ca/biology/chapter/22-1-osmoregulation-and-osmotic-balance/#

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ACTIVITY 1: ANSWER KEY
1. FACT- The tendency to maintain a stable, relatively constant internal environment
is called homeostasis. The body maintains homeostasis for many factors in addition Note: Practice Personal Hygiene Protocols 59
to temperature. For instance, the concentration of various ions in your blood must be always
kept steady, along with pH and the concentration of glucose. If these values get too
high or low, you can end up getting very sick.

2. FACT- Maintenance of homeostasis usually involves negative feedback loops.
These loops act to oppose the stimulus, or cue, that triggers them. For example, if
your body temperature is too high, a negative feedback loop will act to bring it back
down towards the set point, or target value, 98.60F or 37.0∘C.
3. BLUFF-98.80 C
36.5–37.5 °C (97.7–99.5 °F) is a typically reported range for normal body temperature.
4. BLUFF- reach below– rise above.
5. BLUFF – decreases - increases

6. FACT- Diabetes is a disease caused by a broken feedback loop involving the
hormone insulin. The broken feedback loop makes it difficult or impossible for the body
to bring high blood sugar down to a healthy level.

7. FACT- Positive feedback loops are usually found in processes that need to be
pushed to completion, not when the status quo needs to be maintained. A positive
feedback loop comes into play during childbirth. In childbirth, the baby's head presses
on the cervix—the bottom of the uterus, through which the baby must emerge—and
activates neurons to the brain. The neurons send a signal that leads to release of the
hormone oxytocin from the pituitary gland.
8. FACT- Oxytocin increases uterine contractions, and thus pressure on the cervix.
This causes the release of even more oxytocin and produces even stronger
contractions. This positive feedback loop continues until the baby is born.
9. FACT- Oxytocin is a hormone produced by the hypothalamus and secreted by the
pituitary gland. This important hormone plays a crucial role in the childbirth process
and also helps with male reproduction. Understanding oxytocin will help you take
better care of your health and lead you toward a better understanding of how your
body functions.In women, oxytocin is responsible for signaling contractions of the

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GUIDE QUESTIONS:

1.The tendency to maintain a stable, relatively constant internal environment is
called homeostasis. The body maintains homeostasis for many factors in
addition to temperature. For instance, the concentration of various ions in your
blood must be kept steady, along with pH and the concentration of glucose.

2.The endocrine system plays an important role in homeostasis because
hormones regulate the activity of body cells. The release of hormones into the
blood is controlled by a stimulus. For example, the stimulus either causes an
increase or a decrease in the amount of hormone secreted.

3. Sample Answers: Aging is a general example of disease as a result of
homeostatic imbalance. As an organism ages, weakening of feedback
loops gradually results in an unstable internal environment. This lack of
homeostasis increases the risk for illness and is responsible for the
physical changes associated with aging. Heart failure is the result of
negative feedback mechanisms that become overwhelmed, allowing
destructive positive feedback mechanisms to compensate for the failed
feedback mechanisms. This leads to high blood pressure and
enlargement of the heart, which eventually becomes too stiff to pump
blood effectively, resulting in heart failure. Severe heart failure can be
fatal.

Diabetes, a metabolic disorder caused by excess blood glucose levels, is a key
example of disease caused by failed homeostasis. In ideal circumstances,
homeostatic control mechanisms should prevent this imbalance from occurring.
However, in some people, the mechanisms do not work efficiently enough or the
amount of blood glucose is too great to be effectively managed. In these cases,
medical intervention is necessary to restore homeostasis and prevent permanent
organ damage.

Activity 2

Rise in body temperature

Skin and brain sense change

Command from the brain

Prepared by:

FRANCIS M. SUGUE
Mallig National High School

HECTOR M. SALCEDO
Diadi Region High School

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Guide Question:
1.Hormones are chemical messengers that travel throughout the body
coordinating complex processes like growth, metabolism, and fertility. They
can influence the function of the immune system, and even alter behavior.
Before birth, they guide development of the brain and reproductive system.

Activity 3

Guide Questions:
1.Possible answers: Childbirth is a positive feedback loop. During childbirth, the
uterus will contract until the child is born.
Blood clotting is another example because platelets will continue to be released to
the injury site until the bleeding has stopped
2. Answers may vary.
Activity 4
Guide Questions:
1.
▪ Thermoregulation (if body temperature changes, mechanisms are induced to restore
normal levels)
▪ Blood sugar regulation (insulin lowers blood glucose when levels are high ; glucagon
raises blood glucose when levels are low)
▪ Osmoregulation (ADH is secreted to retain water when dehydrated and its release is
inhibited when the body is hydrated)