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4/16/2020 Lesson - Homeostasis - Study Island

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Homeostasis

Homeostasis is the regulation of metabolic processes to maintain the stableinternal conditions required for survival.

Maintaining HomeostasisIn order to survive, organisms must be able to adapt or respond to changing externalconditions. The body has mechanisms for maintaining a stable internal temperature, pH, andion concentration. These mechanisms often require several organ systems to interact withone another in order to maintain homeostasis.

If there is a disturbance in one or more of the body's systems, homeostatic imbalance canoccur. Most diseases are considered results of homeostatic imbalance.

TemperatureCells function properly only in a narrow range of temperatures, so the body has a number ofprocesses that function to maintain internal temperatures within this range. In cases ofexposure to extreme heat or cold, the homeostatic balance is disturbed, and cell die-off,organ damage, or even death can result.

Because the skin is the first organ to be exposed to environmental changes, it is stronglylinked with the nervous system. Skin cells communicate with the nervous system in order torespond to temperature changes.

When it is cold outside, messages are sent from the nervous system to the circulatory andmuscular systems. Blood flow is diverted from the skin to the interior of the body, where it ismore insulated. The body also starts to shiver. As muscles convert chemical energy to kineticenergy, some energy is released as heat.

Sweating keeps the body cool by evaporating water from the surface of the skin. Shiveringhelps to raise body temperature by forcing the body to move.

Homeostasis



When it is hot outside, messages are sent to the circulatory and integumentary systems.Blood vessels in the skin dilate to allow more blood flow to the surface of the body, whichallows more heat to be exchanged with the environment. The nervous system also sendmessages to the skin to perspire or sweat. When sweat evaporates from the surface of theskin, it also carries heat energy away from the body.

The following video discusses some of the body's mechanisms for maintaining internaltemperatures. Click on the image to start the video.

Clip provided by Education Clip Library with permission from ITN Source

pH BalanceCells rely on enzymes to perform many essential tasks. Enzymes can function only in anarrow range of temperatures and pH. So, it is necessary for the pH of the fluid within andsurrounding the cells of multicellular organisms remain constant. For example, human bloodhas a relatively constant pH of 7.4

Buffers are substances that help organisms regulate their pH, so they can maintainhomeostasis. The carbonic acid-bicarbonate system is an example of a biological buffersystem.

When blood pH decreases due to illness or elevated carbon dioxide levels, the bodyincreases the rate of respiration. This removes excess carbon dioxide from the blood, and thepH balance is restored.

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Some health conditions can cause the blood pH to be outside the normal range. For instance,people suffering from emphysema have lung damage, and they can no longer expel carbondioxide normally. As a result, blood pH is lower than normal.

Concentration of SolutesMany of the body's mechanisms for maintaining homeostasis take place at the cellular level.A cell's membrane is key in maintaining homeostasis because the membrane allows cells toregulate the materials that are entering or leaving.

For example, human cells must have a lower sodium ion concentration and a higherpotassium ion concentration than the blood. To do this, cells have membrane pumps thatmove sodium out of the cell and move potassium into it.

A steady concentration of other solutes in the blood must also be maintained. When solutesbecome imbalanced, diseases occur. Diabetes, for example, is caused by a disruption in theendocrine system and results in large fluctuations of blood glucose levels.

Homeostasis & Feedback Mechanisms

In order to maintain homeostasis, positive and negative feedbackmechanisms are both involved in organism responses to stimuli.

Maintenance of HomeostasisThe properties of a total living system are different from the properties of the individual parts.In order to keep all parts of the organism functional and working together, an organism mustbe able to keep internal conditions constant despite external pressures. Examples ofprocesses that help organisms maintain homeostasis, an internal equilibrium, includethermoregulation, oxygen regulation, and maintenance of a proper water balance.



Organisms accomplish these tasks by various feedback mechanisms.

When the output from one part of a system influences the input to other parts of a system, it is known as feedback.

Positive Feedback MechanismsA positive feedback mechanism is an interaction that increases or amplifies theresponse of the system in which it is incorporated.

Coagulation, or blood clotting, is an example of positive feedback. Damage to a vessel wallwill signal for the release of substances that trigger the activation of blood platelets. Asplatelets begin to accumulate around the damaged portion, they send chemical signals toactivate more platelets resulting in the formation of a clot, which acts as a temporary plug untilthe vessel tissue can be repaired.

Negative Feedback MechanismsA negative feedback mechanism is an interaction that reduces or dampens theresponse of the system in which it is incorporated.

Negative feedback loops are more common mechanisms in maintaining homeostasis.Whereas positive feedback loops reinforce changes to a system, negative feedback loops areresponses in which a system works against change. The insulin production model below bestexplains a negative feedback mechanism.



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4/16/2020 Printable Worksheet - Homeostasis - Study Island

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HomeostasisQuestion 1 .

In order to maintain homeostasis, the human body must be able to get rid of the waste productsproduced by cellular processes. The kidneys, for example, are responsible for removing waste from thebloodstream by producing urine. Urine produced in the kidneys then travels through the ureter and intobladder, and is finally expelled from the body by the urethra.

The kidneys, ureter, bladder, and urethra help the body maintain homeostasis through the processof _______.

A. respiration

B. digestion

C. excretion

D. specialization

Question 2 .

Anna often finds that she becomes drowsy in the afternoons. The warmer her classroom is, the hardershe finds it to stay awake. Why does warmth make her more tired?

A. Her body produces less energy in order to keep her from overheating.

B. The environment is so hot that it interferes with the normal chemical reactions of

cellular respiration.

C. Most of her body's energy is being used to reduce her temperature through sweating,

panting, and similar methods.

D. The heat signals the cells in her body to stop cellular respiration in order to conserve

oxygen.

Question 3 .

Directions: Select each correct answer. More than one answer may be correct.

For humans, having a constant internal temperature is crucial for the maintenance of homeostasis.When a person's body temperature is too high, enzymes can stop functioning properly. As a result, thebody's metabolic processes are disrupted.

In which of the following ways does the body respond when its temperature is too high?

by increasing the digestion of food

by increasing the production of sweat

by increasing blood flow to the skin

by increasing the respiratory rate

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Question 4 .

Directions: Drag the tiles to the boxes to form correct pairs.

The tiles below show three definitions. Match each definition with the correct term.

positive feedback mechanism

homeostasis

negative feedback mechanism

Question 5 .

Homeostasis is the regulation of metabolic processes within an organism in order to maintain thestable internal conditions required for life.

The human respiratory system includes the nose, the larynx, and the lungs. This body system helpsmaintain homeostasis by

A. removing solid waste from the body.

B. enabling gas exchange in the body.

C. regulating hormone levels in the body.

D. transporting oxygen to other organ systems.

Question 6 .

Homeostasis is the process through which an organism regulates its internal environment in order tomaintain a stable and constant condition.

An example of homeostasis is the regulation of the glucose sugar level in blood through the interactionof the hormones insulin and glucagon.

What happens if the body is unable to maintain its blood glucose levels?

A. New hormones are created to solve the problem.

B. The body adapts to a different blood glucose level.

C. Diseases, such as diabetes and hypoglycemia, result.

D. This regulation is unnecessary to the viability of organisms.

regulation of metabolicprocesses to maintain thestable internal conditions

required for survival

an interaction thatincreases or amplifies theresponse of the system in

which it is incorporated

an interaction that reducesor dampens the responseof the system in which it is

incorporated




Question 7 .

When dry environmental conditions exist, guard cells close the openings in leaves to reduce the loss ofwater from the plant. This process is an example of a feedback mechanism that plants use in order to

A. absorb more solar energy.

B. maintain homeostasis.

C. expend their resources.

D. produce more chlorophyll.

Question 8 .


Feedback loops often control mechanisms in the human body. Some mechanisms are controlled bypositive feedback loops, while others are controlled by negative feedback loops.

Four mechanisms common in the human body are described below. Which of these is controlled by anegative feedback loop?

A tear in the lining of a blood vessel wall causes clotting to occur asplatelets attach to the site of the tear and release chemicals. Thereleased chemicals attract more platelets, which results in moreclotting.

When a woman is in labor and uterine contractions begin, her bodyreleases the hormone oxytocin. Oxytocin causes a nerve stimulus,which stimulates the body to produce more oxytocin. This furtherincreases the occurrence of contractions.

An increase in blood glucose triggers the pancreas to produce insulin,which causes glucose to be stored as glycogen. As glucose levelsdecrease, insulin production stops, which results in glycogen beingconverted back to glucose.

Low oxygen levels trigger the kidneys to release thehormone erythropoietin, which stimulates the production of red bloodcells. As oxygen levels return to normal due to an increased numberof red blood cells available to transport oxygen, the kidneys stopmaking erythropoietin, and red blood cell production declines.

Question 9 .

Directions: Drag each label to the correct box.

Kai is running in a marathon. As he starts running, his body temperature increases. His body respondsby initiating a series of steps to return his body to homeostasis. Place the steps that Kai's body goesthrough in order from the step that occurs first to the step that occurs last.




Question 10 .


Which of the following is an example of two or more body systems interacting to maintainhomeostasis?

When calcium levels in the blood are low, hormones cause calcium tobe released from bones.

When too much salt is consumed, it is filtered out of the blood by thekidneys and excreted.

When body temperature is high, signals from the brain causeincreased blood flow to the skin.

Question 11 .

An organism's ability to maintain a stable internal environment in the midst of external environmentalchange is known as

A. homeostasis.

B. commensalism.

C. reproduction.

D. metabolism.

Question 12 .

During times of vigorous physical activity, muscles require a constant supply of oxygen. How does thebody respond to these needs?

A. Breathing rate and heart rate both increase.

B. Heart rate decreases, but breathing rate remains stable.

C. Breathing rate increases, but heart rate remains stable.

D. Breathing rate and heart rate both decrease.

Question 13 .


The components of the human body, from organ systems to cell organelles, interact to maintain abalanced internal environment. To successfully accomplish this task, organisms possess many differentreceptors that detect deviations in the body's internal state and initiate corrective actions.

In which of the following ways does the body respond to an increase in skeletal muscle cell activity?

by increasing the respiratory rate

by producing less hemoglobin

by converting white bloods cells to red blood cells

by increasing the heart rate




Question 14 .

Jennifer usually has cold hands. After running laps in gym class, her hands are very warm, and the ringshe wears on her right hand fits more tightly than usual. What change in her body is most directlyresponsible for this change, and what purpose does it serve?

A. Her body temperature rises to increase the amount of energy available to her muscles.

B. Her heart rate increases to get more food and oxygen to her muscle cells.

C. The relative amount of salt in her body increases as water is lost through sweating.

D. Her blood vessels dilate to increase the amount of heat her body loses through her

skin.

Question 15 .

Homeostasis refers to an organism's ability to maintain a relatively constant internal environment.Sweating is a homeostatic process that humans undergo when it is hot.

How does sweating help humans maintain homeostasis?

A. Since the temperature of sweat is relatively low, allowing sweat to sit on the surface of

the skin has a natural cooling effect.

B. When a person sweats, chemical changes occur within the body that allow for the

absorption of heat.

C. Sweat is exposed to air, so heat is absorbed by the air and transferred to the body,

cooling the person.

D. Body heat is absorbed by sweat and then transferred to the air, which cools the

person.

Question 16 .

In the human body, when the blood sugar level rises, a hormone known as insulin is released by thepancreas. This hormone speeds up the movement of sugar out of the blood, so the blood sugar leveldecreases and returns to equilibrium.

This is an example of

A. gene expression.

B. a feedback mechanism.

C. a learned behavior.

D. natural selection.




Question 17 .

The secretion of hormones is an example of a physiological feedback loop. When hormones areneeded, they are secreted by glands. When the hormones are no longer needed, the glands aresignaled to stop secreting the hormones until they are needed again.

Thus, the basic function of a physiological feedback loop is

A. to create substances.

B. to destroy substances.

C. to end a process.

D. to regulate a process.

Question 18 .

How do the urinary and circulatory systems interact to maintain homeostasis in humans?

A. Blood flows to the kidneys. Cellular wastes are filtered from the blood and stored in the

bladder until they are excreted from the body.

B. The kidneys produce growth hormones that are carried through the bloodstream to

parts of the body where they are needed.

C. The kidneys produce wastes that are carried within the bloodstream to the arteries,

where they are recycled into useful products.

D. The kidneys transform food molecules into ATP. This form of energy is carried by the

bloodstream to muscles when activity is needed.




Question 19 .

Directions: Drag each tile to the correct box.

Calvin ate a candy bar, which caused his body's blood glucose levels to become unbalanced. His bodyresponded by initiating a feedback mechanism to return his body to homeostasis. Place the steps ofthis feedback mechanism in order, starting with the blood glucose imbalance that occurred after Calvinconsumed the candy bar.

↓

↓

↓

↓

Calvin's blood glucose levels decreased.

Calvin's pancreas stoppedsecreting insulin.

Calvin's body cells started to take up glucose and

store it as glycogen.

Calvin's blood glucose levels increased.

Calvin's pancreas started secreting insulin.




Question 20 .

Directions: Select the correct answer from each drop-down menu.

Stomata are microscopic holes in plant leaves that allow gas exchange with the atmosphere.Stomata allow the carbon dioxide necessary for photosynthesis to enter the cells of the plant.When the stomata are open, transpiration also occurs, which causes the plant to lose water.

Stomata are bordered by guard cells, which can open or close the stomata. In order tomaintain homeostasis, the guard cells the stomata when water levels in the plant'scells become too low, and they the stomata when carbon dioxide levels in the cellsbecome too low.


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Temperature Maintaining Homeostasis Homeostasisgreenridge.k12.mo.us › UserFiles › Servers › Server...The kidneys, for example, are responsible for removing waste from the bloodstream