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Explain Thermoregulation in the Body

In this worksheet, students will explain the importance of homeostasis and the regulation of internal body temperature.

'Explain Thermoregulation in the Body' worksheet

Key stage:  KS 4

GCSE Subjects:   Biology: Single Subject

GCSE Boards:   Pearson Edexcel

Curriculum topic:   Animal Coordination, Control and Homeostasis

Curriculum subtopic:   Animal Coordination, Control and Homeostasis

Difficulty level:  

Worksheet Overview

QUESTION 1 of 10

When the environment changes, why don’t we boil, freeze or change our shape?

 

This concept is HOMEOSTASIS: the maintenance of a constant internal environment in the body.

 

Hormones (chemicals) and the nervous system detect changes outside the body and counteract any extreme change automatically, so you never even know it’s happening!

 

Two monitoring processes that are vital are THERMOREGULATION and OSMOREGULATION!

 

 

Osmoregulation

Osmoregulation maintains water levels inside and outside the cell (in the blood).

 

Cells work best when these water concentrations are the SAME, meaning the cell is in an ISOtonic solution.

 

But if there's too much water outside, the cell is in a HYPERtonic solution, and to fix this the cell takes in water via osmosis and swells up.


However, if the water concentration is too low outside the cell or the solution is HYPOtonic, the cell will expel water via osmosis, making them shrivel up.

 

Thermoregulation

Thermoregulation is the control of our internal body temperature, which is always aimed at an ideal 37°c for our enzymes- any lower and they lack the energy to work fast, and they will denature if we get too hot. 

 

Body temperature is monitored by the THERMOREGULATORY CENTRE in the HYPOTHALAMUS in the brain and has receptors that monitor blood temperature.

 

It acts as a COORDINATION CENTRE for incoming information and outgoing responses, causing EFFECTORS like the sweat glands and muscles to perform commands to transfer energy to and from the environment.

 

The skin is made of 3 layers called the EPIDERMIS, the DERMIS and a FATTY TISSUE LAYER, and it has its own temperature receptors, meaning the skin sends nerve impulses with skin temperature updates to the thermoregulatory centre.

 

 

If our blood temperature gets too hot:

 

1. Our blood vessels widen in VASODILATION, making more blood pass closer to the skin and so more heat is lost.


2. Also, the sweat glands in the dermis produce sweat that evaporates off the surface of the EPIdermis and takes heat energy into the environment.

 

 

If we get too cold,

 

1. VASOCONSTRICTION occurs as the blood vessels narrow, meaning less blood goes near the skin and so less heat is lost.


2. We stop making sweat to conserve thermal energy


3. We start to shiver as our muscles start to contract and relax rapidly to create heat using energy from respiration.


4. Hair erector muscles in the dermis receive impulses to contract to make your hair stand on end, trapping a layer of air close to the skin to insulate you.

 

What are the definitions of homeostasis, osmoregulation and thermoregulation?

Column A

Column B

Homeostasis
The maintenance of internal bodily conditions
Thermoregulation
The maintenance of water concentrations inside and...
Osmoregulation
The maintenance of body temperature at 37°c

Why do we need to keep our bodies close to 37°c?

It's the optimal temperature for enzymes

It's the optimal temperature for chemical reactions

It's the optimal temperature for the brain

The key to stabilising our body temperature is found in the brain.

It's the optimal temperature for enzymes

It's the optimal temperature for chemical reactions

It's the optimal temperature for the brain

Is it EFFECTORS or RECEPTORS in the thermoregulatory centre that monitor body temperature?

It's the optimal temperature for enzymes

It's the optimal temperature for chemical reactions

It's the optimal temperature for the brain

By which method does water move in and out of cells in osmoregulation?

Simple Diffusion

Osmosis

Active Transport

How does the thermoregulatory centre cool us down or heat us up?

Simple Diffusion

Osmosis

Active Transport

Hair erector muscles and sweat glands are found in which layer of the skin?

The Dermis

The Epidermis

The Fatty Tissue Layer

When the temperature drops too low, many effectors are triggered by the thermoregulatory centre to stabilise our internal temperature.

 

Which of the following happen when we become too cold?

We've talked about what happens when we get cold, but there are important changes in the body when we get hot too.

 

Let's compare the results on our skin capillaries when we get too hot or too cold.

In Vasodilation, blood flow to the capillaries INCREASES/ DECREASES, so MORE/ LESS heat is lost from the skin. In Vasoconstriction, blood flow to the capillaries INCREASES/ DECREASES, so MORE/ LESS heat is lost from the skin.

Cells are very sensitive when they compare their water content with the amount of water outside the cell and will change shape to counteract any differences.

  • Question 1

What are the definitions of homeostasis, osmoregulation and thermoregulation?

CORRECT ANSWER

Column A

Column B

Homeostasis
The maintenance of internal bodil...
Thermoregulation
The maintenance of body temperatu...
Osmoregulation
The maintenance of water concentr...
EDDIE SAYS
How did you get on defining these terms? Homeostasis is the maintenance of a constant internal environment in the body, automatically performed by hormones and the nervous system. Homeostasis has two measures in particular that it uses to keep our bodies stable: THERMOREGULATION which is the control of our internal body temperature, which is always aimed at an ideal 37 degrees celsius, AND OSMOREGULATION controls the input and output of water and minerals in our blood to keep our cells working.
  • Question 2

Why do we need to keep our bodies close to 37°c?

CORRECT ANSWER
It's the optimal temperature for enzymes
EDDIE SAYS
It's important that we keep our bodies at the optimal working temperature for enzymes, as they are the catalysts in almost every reaction we use to survive! If the temperature falls too low, they don't have enough energy to work, but if it goes too high, their unique 3D structure will break down and they will denature!
  • Question 3

The key to stabilising our body temperature is found in the brain.

CORRECT ANSWER
EDDIE SAYS
Since we've said that our vital enzymes are very sensitive to changes in body temperature, it's clear that it must be carefully regulated. This is done by the THERMOREGULATORY centre in a part of the brain called the hypothalamus, which acts as the coordination centre in the body.
  • Question 4

Is it EFFECTORS or RECEPTORS in the thermoregulatory centre that monitor body temperature?

CORRECT ANSWER
EDDIE SAYS
This was a cheeky one because it's RECEPTORS in the thermoregulatory centre that detect changes temperature, not effectors! EFFECTORS carry out responses in the body that the thermoregulatory centre has instructed them to perform after registering an extreme change in our internal temperature.
  • Question 5

By which method does water move in and out of cells in osmoregulation?

CORRECT ANSWER
Osmosis
EDDIE SAYS
Did you manage this one? The trick is to remember that OSMOregulation uses OSMOsis to move water in and out of cells depending on the distribution of water.
  • Question 6

How does the thermoregulatory centre cool us down or heat us up?

CORRECT ANSWER
EDDIE SAYS
If it weren\\\'t for the thermoregulatory centre, we would be the same temperature as our environment and not be able to withstand any change in weather! When it detects changes outside the body, it uses our relationship with the surrounding environment to make us give off more heat or reduce how much heat we give off, which is all a matter of energy transfer! Note: we can give lots of heat to the environment or give less heat to the environment, but our thermoregulatory centre can\\\'t make us take heat from our environment! So it\\\'s a matter of adjusting how much we give, as making a fire or putting on clothing are not commands initiated by the hypothalamus, so be careful with your understanding here!
  • Question 7

Hair erector muscles and sweat glands are found in which layer of the skin?

CORRECT ANSWER
The Dermis
EDDIE SAYS
When the thermoregulatory centre sends signals to the effectors to do their work, we need to know where the structures that create a difference actually lie in the body. The skin is made from three key layers: the epidermis on the outside, then the dermis and most inward is the fatty tissue layer, which comes just before the muscle. Try to make these terms distinct from each other in your mind, as it\'s important to know that the DERMIS is where hair erector muscles and sweat glands are, and it\'s from the epidermis that the sweat evaporates off.
  • Question 8

When the temperature drops too low, many effectors are triggered by the thermoregulatory centre to stabilise our internal temperature.

 

Which of the following happen when we become too cold?

CORRECT ANSWER
EDDIE SAYS
How did you find this question? A lot of information here but that means a lot of marks up for grabs! There are 4 ways of getting our body temperature back up to normal: -Vasoconstriction (see next question for more information) - To stop any more heat being lost, like in vasoconstriction, our hairs are made to stand on end, trapping a layer of air between the skin and the environment, meaning any heat lost heats that air layer and keeps our skin temperature closer to 37 degrees celsius. - Our muscles are also told to contract ad relax rapidly, making us shiver, and this intense muscle movement using energy from respiration produces heat. Think about when you're so cold your teeth begin to chatter- that's because the muscles in our jaw are trying to heat you up! - Finally, unlike the option in the grid above, our sweat glands STOP making sweat because we don't want any heat to evaporate away with our sweat. Losing heat by sweat is something our bodies do when we are too hot, and to learn about vasoconstriction carry on to the final question!
  • Question 9

We've talked about what happens when we get cold, but there are important changes in the body when we get hot too.

 

Let's compare the results on our skin capillaries when we get too hot or too cold.

CORRECT ANSWER
In Vasodilation, blood flow to the capillaries INCREASES/ DECREASES, so MORE/ LESS heat is lost from the skin.

In Vasoconstriction, blood flow to the capillaries INCREASES/ DECREASES, so MORE/ LESS heat is lost from the skin.
EDDIE SAYS
Did you do as well as you'd hoped in this final question? VASODILATION is for when our blood is too HOT- our blood vessel walls dilate or open up, meaning more blood flows through them at a given time. When these vessels are close to the skin, they give off more heat to the environment, helping to cool us down. The opposite happens in VASOCONTRICTION, which happens when our blood has lost TOO MUCH heat! Our blood vessels are told to squeeze tightly and reduce how much blood is travelling through them, meaning less heat is lost from the body. BUT understand that vasoconstriction is about the body trying to keep the heat it already has and not lose anymore- it's NOT GAINING HEAT! Well done on this topic, and hopefully it's clear to you now how our body's keep us at the body temperature we need.
  • Question 10

Cells are very sensitive when they compare their water content with the amount of water outside the cell and will change shape to counteract any differences.

CORRECT ANSWER
EDDIE SAYS
We ideally want our blood to be regulated so our cells live in an isotonic fluid, meaning the water levels inside and outside the cell match. When these levels change, we don't say isotonic anymore, we say hyper- or hypotonic. BUT there's an important rule: These terms refer to the LEVEL OF SOLUTE OUTSIDE THE CELL and indirectly the CELL SHAPE, not the water levels directly!!! So hypo- means there's less SOLUTE (e.g. ions) OUTSIDE the cell, so the solution is more DILUTE/has more water than solute, so the cell swells up to compensate! The opposite happens in a hypertonic solution when LOTS of SOLUTE OUTSIDE means less water outside the cell, so it sends water out and shrivels up. If you feel confused, maybe think about how hyper- and hypotonic relate to the cell getting smaller or bigger and then what that means about the solution it's sitting in!
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