A Level Biology: Homeostasis 2 – Thermoregulation
Hi!
Welcome to the second video on Homeostasis.
Today, we are going to be looking at Thermoregulation.
But first, a quick recap.
You should remember that homeostasis basically means staying the same.
It was introduced or the word was introduced by Claude Bernard and it basically means maintaining
a constant, stable internal environment.
Why do we need to maintain a constant temperature?
The most important reason is enzymes.
Enzymes are biological catalysts in that they speed up chemical reactions.
They also have an optimum temperature which is approximately 37?C.
If our core temperature gets too high, we suffer from hyperthermia and the enzymes start
to denature and no longer work.
If our core temperature gets too low, then we suffer from hypothermia and the enzymes’
rate of reaction starts to slow down.
Notice that I mentioned core temperature.
Your core temperature basically is your head, your thorax and your abdomen.
That’s where most of your important organs or the vital organs are stored.
Your extremities are things like your fingers, toes, nose and your ears.
Those temperatures can fluctuate more.
Okay.
We’ve got a quick recap of an effective feedback loop.
You got your normal internal environment which is stable.
You got a change detected by receptors to that environment; signals an intent to the
control center, which is usually the hypothalamus that sends signals to the effectors to decrease
or increase to bring the body back to its normal environment or to its normal state.
So we are going to look at how thermoregulation takes place now.
Here you got your normal, stable internal environment; that’s 37?C. Let’s say you
get too hot.
Receptors detect those changes within the skin and also in the blood.
That information is sent to your hypothalamus.
Your hypothalamus then sends a signal to the effectors to bring about three changes.
The first one is vasodilation; then hairs on the skin start to lie flat; and also increased
sweat production.
If you take a close look, you can see here in this diagram: E.) you’ve got the sweat
gland production.
You can see that sweat is being produced and what it does is it increases heat loss through
evaporation.
D.) The muscles start to relax, thereby forcing the hair to lay down flat and closer to the
surface of the skin.
That reduces the amount of still air trapped in between these layers here.
In other words, it promotes the movement of air and that aids heat loss through convection.
F.) You got vasodilation and what that means is that these capillaries here, they drive
your blood upwards towards the surface of the skin where it can lose heat through conduction
and also convection.
When you get too cold, receptors within the skin and also in the blood, once again, detect
that change, send the information to the hypothalamus which sends information through the effectors
to bring about changes.
These changes are decreased reproduction, vasoconstriction and also shivering as well.
If we have a close look, you can see that we start off with A. There, arrector pili
muscles contract thereby lifting the hairs on your skin and therefore traps air in between
them.
C which is vasoconstriction, the capillaries which are close to the surface of the skin
get locked off and blood is diverted back deeper into the skin, thereby conserving heat.
As you can see here, sweat production has stopped completely.
That concludes the short presentation.
I hoped you enjoyed it.
Don’t forget to keep a lookout for some more videos coming out soon.
[end of audio – 05:09] A Level Biology: Homeostasis 2 - Thermoregulation
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