[BLANK_AUDIO] >> Okay, so that's just an overview of how we regulate respiration rate. I want to go through it one time, just to make sure we have all the concepts. We have two types of chemoreceptors that are important. What do we call them? Stephanie? >> Central and peripheral? >> Central chemoreceptors and peripheral chemoreceptors, exactly. Now, who wants to take stab at telling me where the central chemoreceptors are located? Naomi. >> In the carotid artery? >> Oh, no. Stephanie? >> In the brain stem? >> Yes. They're in the brain stem. So, it's the central chemoreceptors that are under that. Functional protective structure called the, Lauren. >> Blood brain barrier? >> Exactly, okay, now, Naomi you're on. We have the peripheral chemo receptors, and we have them located in two spots. >> In the carotid artery and the aorta? >> Exactly. So, in the aortic arch, we have the aortic bodies, right? And up in the carotid arteries, near the point where the common carotid artery branches, we have the carotid bodies. Excellent. Now, the peripheral chemoreceptors. Are sampling the chemistry of the systemic blood, and the central chemo receptors are sampling the chemistry of what fluid? Naomi. >> The cerebral spinal fluid. >> Exactly. The cerebral spinal fluid. Okay, now. Andre, what is the most powerful. Stimulus for respiration. >> Is it carbon dioxide? >> Yes. So it's increased carbon dio, dioxide content in the systemic blood, right? And does that increase in carbon dioxide affect the central, or the peripheral chema receptors? Andre. >> It affects the central chema receptor? >> Exactly. And how does it do that? Who wants to take us through that? Stephanie >> Through the hydrogen ions? >> Exactly because when CO2 diffuses across the blood brain barrier it does what CO2 likes to do which is when it's dissolved in water. It creates? >> Carbonic acid? >> Carbonic acid. And carbonic acid is a weak acid, so it will dissociate some free hydrogen ions which will directly stimulate the central chemoreceptors. Great job. Now, the peripheral chemo receptors tend to be more responsive to what? Changes in what? Stephanie? >> The PH in the one? >> PH is one. Now they will respond to changes in PH. And the most important thing about the PH change is acidification. But much more likely to have acids in the blood than not. So where would those acids come from. Andre? >> From anabolic processes? >> Exactly. So like Stephanie, when she did her metabolic test for us. We know that she was producing some metabolic acids as her metabolisms speeded up. And specifically, they were probably lactic acid in that case. But if somebody were starving, they could be producing keto's, which are also acids. Right? Now tell me about, oxygen. Changes in oxygen level. What do you. Stephanie? >> If there's a great enough change in oxygen, like if it's too low in the system it can simulate the peripheral chemoreceptors. >> Exactly, and that will also speed respiration. Right, exactly. So, now we haven't talked about this, but I just want to stump the stars, okay? So, let's say that you moved to the top of the Andes. Do you expect that when you first move there. You'll notice big changes in your respiration rate. Naomi? >> I think so, I think you would expect that there would be less oxygen up at like, the atmospheric level so high. So your respiratory rate would increase. >> Exactly, exactly, and you would over time develop some compensations, but initially until you acclimatize to that high altitude, you would expect to get short of breath if you did you know. Just what at sea level would be a very light level of exercise you could expect at altitude that you wouldn't get short of breath with that same amount of exercise. Great Job. Okay. So, I think you've got it. You have an understanding now of how we regulate respiration rate. Our final, segment for the week is going to be Megan's demonstration of the lungs sounds. [BLANK_AUDIO]
