Lesson video

This lesson is called "The Role of the Nervous System in Thermoregulation" and is from the unit "Coordination and Control: Maintaining a Constant Internal Environment." Hi there, my name's Mrs. McCready and I'm here to guide you through today's lesson, so thank you very much for joining me today.

In our lesson today, we're going to describe the roles of receptors, the brain, and effectors in controlling human body temperature.

Now in our lesson today we're gonna come across a number of keywords and they're listed up here on the screen for you now.

You may wish to pause the video and make a note of them, but I will introduce them to you as we come across them.

Now in our lesson today we're gonna first of all see how temperature change is detected before we understand how the body responds to temperature change.

So are you ready to go? I am, let's get started.

Now, internal body temperature can be affected by many external and internal factors, and weather and clothing are examples of external factors that can affect our internal body temperature.

If you just consider when you've worn a really hot jumper on a warm day and wish you'd worn something a bit lighter, you can see how our clothing, for instance, changes our internal body temperature.

Similarly, exercise, stress, and an infection will cause our body temperature to change as well.

And you only have to think about when you've done any form of exercise, even a brisk walk, to see how your body temperature is changed by an internal factor such as exercise.

So all of these factors, external and internal, are impacting our body temperature.

And it's important that we maintain our body temperature at 37 degrees centigrade so that all of our life processes that are going on inside our cells, including those which are controlled by enzymes, can function most effectively.

Because remembering that enzymes function best at their optimum temperature, and if we move away from that, then the rate of reaction decreases.

So maintaining a constant internal environment, in particular a constant body temperature, is really important to our survival.

Now when we are talking about controlling something, we are talking about a system.

And in all systems there must be three major components.

There must be a receptor that can detect changes in the environment.

There must be a coordination centre that directs what response needs to occur in response to the change that has happened and been detected.

And there must be an effector which then goes on and creates the effect required.

So a receptor, a coordination centre, and an effector are three essential components of any system, and that can be a computer system as much as a body system, but we'll notice these in all our body responses.

Now when we're talking about receptors specifically regarding body temperature, we can say that receptors detecting internal body temperature change are located in our skin and also within our brain.

So that's where we're going to go next when we're looking at receptors.

Now the brain receives information from all parts of the body, both inside and outside, so it can detect changes in circumstance both within the body and out with the body.

Now the brain is the major control and coordination centre for the body's responses, but it also has receptors within it.

And those receptors monitor certain aspects of our body's internal environment, temperature being one of them.

So the brain is both a receptor and a coordination centre, especially when we're talking about body temperature.

Now embedded within the brain is a specific area called the hypothalamus, and you can see that indicated there on the diagram.

Now the hypothalamus has a section within it which is known as the thermoregulatory centre.

Thermo meaning heat, regulatory meaning control.

So the thermoregulatory centre located within the hypothalamus is what is regulating our response to changes in internal body temperature.

Now, the hypothalamus has receptors within it that can detect changes in blood temperature, so this is what is alerting the brain to changes in internal temperature, it's changes in the temperature of the blood.

And those receptors within the hypothalamus are connected to the coordination centre, the thermoregulatory centre, and neurons link the two together to enable a response to be then coordinated.

So let's quickly check that.

In which part of the brain is the thermoregulatory centre located? Is it A, the hypothalamus, B, the hypothermia, or C, the hypothesis? I'll give you five seconds to think about it.

Okay, you should have chosen that the hypothalamus is where the thermoregulatory centre is located.

Well done if you chose that.

Now, I've already said that the brain is just one of two receptors which can detect changes in temperature and the skin is where the other receptors are located.

So within the skin are temperature receptors, and these are embedded within the skin layer and they can detect changes to external temperature.

So the hypothalamus is detecting changes to internal temperature by monitoring the temperature of blood, and the receptors within the skin are detecting changes in the external temperature and reporting those up to the thermoregulatory centre as well.

So they report those messages, those changes in external temperature, along sensory neurons to the thermoregulatory centre within the hypothalamus.

So let's quickly check that.

Which label shows the temperature receptor? I'll give you five seconds to decide.

Okay, hopefully you have identified that Part E is the temperature receptor.

Well done if you spotted that.

So what I'd like you to do now is to firstly describe where temperature receptors are located in the body and what type of temperature changes they detect.

And then I'd like you to consider that in some extreme injuries, the brain gets damaged, and what I would like you to do is to suggest what impact this might have on the body's ability to regulate temperature.

So pause the video and come back to me when you're ready.

Okay, let's see how you got on then.

So firstly I asked you to describe where temperature receptors are located and what type of temperature changes they detect.

So you should have listed that temperature receptors are located in the hypothalamus, in the brain, and in the skin, and that the hypothalamus detects changes in blood temperature and the skin receptors detect changes in external temperature.

So the hypothalamus is internal and the skin receptors are external.

Well done if you got all of that correct.

Then I asked you to consider that in some extreme injuries the brain gets damaged and what impact this might have on the body's ability to regulate temperature.

And so you might have written that damage to the brain may impair the ability of the hypothalamus to detect changes in blood temperature.

And if this occurs, this would impair the body's ability to detect changes in internal temperature because the receptors in the hypothalamus would be damaged and therefore not work.

It might also damage the thermoregulatory centre, and that would impair the ability of the brain to coordinate a response.

So well done if you've identified both of those potential scenarios if certain parts of the brain get damaged.

Okay, so now let's see how the body responds to temperature change.

So we've seen that within the hypothalamus is the regulatory centre, and the regulatory centre is the part of the brain that coordinates the response to changes in internal temperature.

So the thermoregulatory centre is the coordination centre, and we've seen that the receptors are present within the hypothalamus and within the skin and both of these are sending messages to the coordination centre, the thermoregulatory centre.

Now sensory neurons are transmitting those impulses to the hypothalamus.

So the hypothalamus is receiving messages via sensory neurons from the temperature receptors in the brain and the temperature receptors in the skin.

And because they're coming from receptors, they're being sent along sensory neurons.

Then the thermoregulatory centre is processing the changes that is being reported by the receptors and sending out messages to effectors via motor neurons from the hypothalamus.

So those messages are going to muscles around the blood vessels which control vasodilation and vasoconstriction.

They are going to the sweat glands to increase or decrease sweating.

And they're going to the skeletal muscles to cause hair to stand up on end or relax and to cause shivering if necessary.

So we can see how the thermoregulatory centre within the hypothalamus is coordinating the incoming messages and the outgoing messages as well.

Now, nerve impulses sent along motor neurons stimulate effectors to respond.

So there are many effectors which can be stimulated.

If the body temperature increases and becomes too high, then erector muscles are not stimulated, so they relax and the hair lies flat, sweat glands secrete sweat to help cool us down, and muscles around blood vessels relax, causing vasodilation.

So these are the messages sent out to various different effectors via motor neurons.

If the body temperature goes too low, then different messages are sent via motor neurons.

So erector muscles contract and that causes hair to stand upright on our skin, sweat glands stop secreting sweat, the muscles around blood vessels contract, causing vasoconstriction, and skeletal muscle contracts and relaxes quickly and repeatedly, causing shivering.

So these are the responses if the temperature is too low.

Now all of these responses are autonomic.

That means they happen without conscious control.

We don't need to think, "Oh, it's a bit cold here, I best start shivering.

Oh, it's a bit hot here, I better start sweating." There is no conscious control over any of these aspects and responses.

They are all autonomic.

They are also antagonistic.

That means they work against each other in order to keep body temperature within a constant narrow range.

So you can think about shivering being in a tug of war with sweating, for instance.

So let's just summarise that.

Receptors are our starting point and these are located within the hypothalamus and in the skin, and these detect changes in temperature.

Now, they send nerve signals along sensory neurons to the thermoregulatory centre, which is located within the hypothalamus.

And the thermoregulatory centre coordinates a response and sends nerve impulses along motor neurons to a range of effectors, which are muscles and glands, in order to create an appropriate response.

So you can see how we're going from receptor to coordination centre to effector in this system.

So let's quickly check our understanding.

Which parts of the body detect temperature changes? A, the thermoregulatory centre, B, the hypothalamus, C, the skin receptors, and D, muscles.

Which parts detect temperature changes? I'll give you five seconds to decide.

Okay, so the parts of the body which detect temperature changes include the hypothalamus and the skin receptor.

Well done if you got both of those.

And now I'd like you to, starting with the receptors, put these stages in order to describe how the body responds to temperature changes.

So Part A is receptors in the skin and hypothalamus detect a change in temperature.

Part B is muscles and glands produce the required effect.

Part C is the thermoregulatory centre sends nerve impulses to the effectors.

And Part D is nerve impulses are sent from receptors to the thermoregulatory centre.

But which order do they go in? I'll give you five seconds to decide.

Okay, so let's see what you've put.

You should have started off with A, the receptors, and then gone to D, the nerve impulses sent to the thermoregulatory centre, and then gone to C, the thermoregulatory centre sending nerve impulses to effectors, before finishing with B, which is the effect.

Well done if you've got those correct.

So what I'd like you to do is, firstly, complete the diagram by adding labels to the hypothalamus and skin receptors and arrows showing how these interact between the parts of the brain and the effectors.

Then, once you've completed the diagram, I'd like you to add numbers of the statements into the boxes to correctly show how the body temperature is maintained.

And there are four statements there and six boxes, so you may need to use some of the statements more than once.

So pause the video and come back to me when you're ready.

Okay, let's check your work then.

So when I asked you to complete the diagram, you should have labelled the receptor in the skin, the hypothalamus in the brain, and then linked both of those to the thermoregulatory centre, and then linked those onto the sweat gland in the skin and the skeletal muscle.

You may also have linked it to the arterial for vasoconstriction and vasodilation.

Then I asked you to add the numbers of the statements into the boxes.

So with an increase in internal temperature, you should have said that number three, the changes detected by the hypothalamus and skin receptors.

Then number one, the thermoregulatory centre coordinates a response.

Then number four, the muscles relax to cause vasodilation and flat body hair, sweat glands excreting sweat.

Whereas for the decrease in internal temperature, you should have started with three about detecting change.

Then you should have gone to number one, the thermoregulatory centre coordinating the response.

Before finishing with number two, the muscles contract to cause vasoconstriction, upright body hair and shivering.

So did you get all of those in the correct order? Just make sure that you have done, and well done indeed.

So we've come to the end of our lesson, and in our lesson today we have seen how important it is to regulate our internal body temperature within a narrow range.

Now, receptors in the skin and the hypothalamus detect changes in the external and blood temperature, and they send nerve impulses via neurons to the thermoregulatory centre located in the hypothalamus.

Now, the thermoregulatory centre coordinates the autonomic response using a series of antagonistic effectors, so that when the temperature increases, sweat glands and muscles in the artery walls are stimulated.

Whereas when the temperature decreases, hair erector muscles, muscles in the artery walls, and skeletal muscles are stimulated to respond.

And together they produce responses to maintain our internal body temperature at a constant 37 degrees.

So I hope you found that interesting today.

Thank you very much for joining me and I'll see you again soon I hope, bye.