Hi. It's Mr. Andersen and welcome to the thermoregulation podcast. Basically
I'm going to talk about how organisms regulate their internal temperature or not. So basically
this right here is a thermal image of a human arm. You can kind of see that right here.
And it's holding on to a snake. And so this shows us the temperature over here. So again
our internal body temperature is going to be around 37 degrees celsius. What's the temperature
of the snake? Well the temperature of the snake is around room temperature. And that's
because they're an ectotherm. And so before we get to that let's talk about heat. If we
have a candle right here. And then you've got your hand right here, there are basically
ways that you can transfer heat from your candle to your hand. And so one way you could
do that would be to stick your finger right in the flame. And when you do that the molecules
of the flame are going to interact with the molecules of your finger. And that's conduction.
So it's actually going to heat you up that way. There's other ways that we could transfer
heat though. If you sit right here and you're not touching the actual flame, you're still
going to feel a little bit of heat. But if you put your finger way about the flame like
this, it's going to be way more painful up here than it is on the side. And the reason
why is a second way that we can transfer heat and that is through convection. Now what's
convection? That's movement of fluids. What's the fluid that's actually heating up your
finger? It's the air. It's getting really hot. Hot air rises. And so it's going to heat
you up way up here at the top. So that's two ways that we could transfer heat. The next
way we could transfer heat is if you were to put your finger over here. And then we'll
have a vacuum in here. You still would get a little bit of heat. If wouldn't be a lot,
but you get a little bit of heat from the candle over here and that's through radiation.
Radiation is important because if this is the sun and this is you on the earth, that
light is moving through the vacuum that is space and it is eventually getting to you.
And so these are all ways that we can get warm. We can get warm by the radiation of
the sun or the movement of air. Or even touching like a warm rock. Something like that. But
there's another way that we can actually generate heat since we're living things. And that is
through respiration. So through metabolism we can generate a little bit of heat. And
so life has evolved two different strategies in order to interact with heat. And the first
strategy is called ectotherm. And that basically means heat from outside. These thing right
here are ectotherms. And so these are turtles. What does that mean? They derive their temperature
from their surroundings. So they're going to be the same temperature as room temperature.
And so what's the advantage of that? The advantage of that is that they don't have to burn up
any energy creating heat inside themselves. And so you don't have to feed a turtle that
often. If you're a big snake you might eat once a month or once a year. If you eat something
big enough. Because they don't require a huge amount of energy. Now what's the disadvantage
of that? If it's really, really cold then all of the metabolism, all of the enzymes
inside your body are going to go slowly as well. And so lot's of times they'll warm themselves
up in the morning by climbing up on a rock or basking in front of the sun. If you're
an endotherm, like this ground squirrel right here, you don't have to worry about that.
You're good to go. And the reason why is that you're generating heat inside you. You have
metabolism going. So what is the temperature of this ground squirrel? It's probably close
to ours. And if it's cold out? It's probably close to ours. And if it's really warm out,
it stays close to ours as well. And so the advantage of being an endotherm is that your
internal temperature is always going to be exactly the same. What's the disadvantage
of that? You have to constantly eat over and over and over and over again. Okay. So how
do we maintain this since we're endotherms? Well basically we use a negative feedback
loop. And so the way you sense it is using something called your hypothalamus. And so
basically on the underside of your brain you have a hypothalamus. It constantly is figuring
out what our body temperature is. And so if our temperature were to go too high, it goes
above a set point, basically we're going to react to that. We're going to react to that
in a number of ways. One way we can react to that, again if we get to hot, is that we're
going to start to sweat. Another way that we're going to do that is we're going to start
to vasodilate. We're going to dilate the capillaries. So we're going to move more blood near the
surface of our body so we can loose that as heat. That's going to bring our temperature
down again. Let's say it goes too low, what do we do? Well if it goes too low, then we're
going to start to get goosebumps, which is going to hold that skin in close to ourselves.
We're also going to start to vasoconstrict. We're going to hold that temperature close
to our body. And so basically that's going to raise our temperature back to that set
point. And we're constantly doing that. And the advantage of that is to keep our body
temperature close to this set point, and that's a perfect set point for all of the enzymes
inside our body to work. And so that's thermoregulation. And I hope that's helpful.