[MUSIC] Okay. So now we're going to talk about thermoregulation. Now, thermoregulation serves to keep our body temperature, in fact, really our brain temperature is what's really defended. Our brain temperature is defended at 37 degrees Centigrade or 98.6 ferinheight. And we use three different types of effector mechanisms, so we can produces heat, and, and that whats makes mammals, one of the things that make mammals very special. We can actually metabolize to produce heat. Non mammals have to kind of wait for the sun to warm them up. The insects only come out when is worm. Reptiles only come out when is warm. But we can actually make our own heat. So, we do that using metabolism. And using skeletal muscle movement contractions. So skeletal muscles actually make make heat. We also use heat conservation, we can keep heat in. And we're going to look at one of the ways that we can keep that, using ananomic function, but in addition we can keep it just by by huddling. We can keep it by putting on a coat. We can keep it by reducing our body surface, if I'm really cold I'm more likely to be like this. If I'm really hot I'm going to spread out, and you can see the squirrels here in Chicago. They either huddle or they are splayed out in the summertime. And then we can also lose heat. So we can lose heat again through ana, ananomic mechanism that we'll look at in some detail. But we can also lose heat behaviorally by splaying out. We can lose heat by sweating. We can lose heat by panting. And I think that about does it. So what you don't see on the li, on this list is, is any ki, type of way to generate coolness. There's no refrigeration in thermoregulation we have no way to thermo to, to refrigerate ourselves. We'll come back to that. Okay, so normally when we're at a relatively comfortable within a relatively comfortable range of temperatures we keep our temperature at around 37, and we do that entirely through something called vasomotion. Meaning, when we're hot, we send our blood out to the skin, what we call the shell. So when it hot, when we're hot, we're sending our blood to the skin. That's going to release that hot to the environment, and we're going to cool down. And when were cold were going to constrict the blood vesse, blood vessels in our skin and we are going to send our blood back to the core. Were going to lose less heat to the environment. So in a hot situation you lose heat. By sending blood to the skin, and in a cold situation, you, you retain, or conserve heat. Now, there is a problem with this. Let's say it gets really, really cold. And, we have, we have that here in Chicago. This winter we really had it. And so what happens? Well, if we really allowed for the, if we really took all the blood away, and it was really, really cold out, what would happen? Well, our skin would freeze. If we, if we abandon our skin to a very cold environment, it's going to freeze, that's frostbite. So what do we do? We have a paradoxical vasodilation. And that's shown, this is actually taken from this winter, this, this is my hand. And you can see that I have vasodilated my fingers, and in the next slide, you'll see I actually had a hat that covered like this. And you can see the line where I'm vasoconstricted here, but I'm, I'm red here. SO I'm red where I'm exposed, I'm vasodilated. I've sent my blood back there, because I don't want my face to freeze. Okay, so, now let's consider the situation where the environment is very hot. Is there a paradoxical vaser constriction? If the environment is very hot. Let's say the environment si at 100 degrees centigrade which is say, farenheit, which is about 40 degrees centigrade. Well, that's hotter than our body. So, if we send the blood out here, we're going to actually gain heat, we're not going to lose it. We can't lose it to something that's hotter than us. So, you would think that there would be this paradox called vasoconstriction. But there is not. What there is, is sweating. And, what sweating enables you to do, is to basically boil off the water that's, that coats your skin. So the heat is actually,. Boiling this water, enough of these water molecules are, are going into vapor, and that is going to, that's going to take, absorb heat from the body. And so that will cool you down. It's not going to work if it's a very humid environment, because then the water is, it's much harder for the water to actually evaporate. And so in situations where it's extremely humid, it's extremely hot, maybe not 40, but, but 45, [COUGH] 45 dry heat. Very hot, that's way too hot. So in these situations can, can you cool yourself down? No, you, you really can't. Which is why air conditioning is in fact, not just a a nice luxury. It's actually a requirement in this situation where we have a heat wave that's very high and this is particularly a requirement. For individuals who have [COUGH] older individuals, individuals on certain medications that make them susceptible to heat stress. And individuals with certain existing conditions. And so the bio the neurobiology of thermal regulation is that. [BLANK_AUDIO] That we cannot sustain, we cannot live in very hot environments. And it then, it becomes, in my opinion, a governmental it is a governmental a responsiblity to cool off individuals in the presence of an extreme hot heat wave. Now I will, there'll be some slides up on the, website that you can look at where there are have been a number of instances where government officials have basically not gotten this biology. They don't understand this biology, and they fault the people. That are, dying in response to a heat wave. And so this, this is a place where it's very, very important that the public understand the importance of cooling down individuals in the presence of a heat wave. Okay, in the next segment. We're going to look at, at disorders of thermoregulation. [MUSIC]
