mikes@tekecs.TEK.COM (Michael Sellers) (11/04/86)
In article <579@tekfdi.UUCP>, mikeb@tekfdi.UUCP (Mike Boyce) writes: > As a side issue: What causes the euphoria induced by aerobic exercise. Your friend and mine, endorphins. These are produced and released in the brain in response to low level pain, and have an opiate effect. This is what is responsible for "runner's high" as well as many other forms of exercise-induced euphoria. In some cases the increased flow of oxygen to the brain can also give you a feeling of exhiliration, particularly after a hard day in front of the terminal, but his doesn't last and isn't the same as the endorphin high. Here's *my* side issue: I was recently asked why you yawn when you are tired. I (somewhat smugly) replied that it was to get rid of excess CO2 in the bloodstream. The question then became why does the amount of CO2 in your blood increase when you are tired? I started to say something about accumulating waste products in your blood, but then remembered that the theory of sleep functioning as a way to get rid of accumulated poisons had been shot down a few years back. So, what to say? Why *does* CO2 accumulate in the blood (plasma)? You would think that its diffusion would remain pretty constant given the concentration of it in the atmosphere, so it wouldn't stay in the blood. But if this is true, why *do* we yawn when we're tired? I have a hypothesis that it is to more fully expand the lower lobes of our lungs that might become somewhat "stagnant" in terms of gas exchange under normal or light breathing conditions, both to increase oxygen intake and CO2 outgo, but I don't have much to back this up with. Anyone else have more reliable information? -- Mike Sellers UUCP: {...your spinal column here...}!tektronix!tekecs!mikes "In a quiet moment, you can just hear them brain cells a-dyin'"
elman@hpcea.HP.COM (Charlie Elman) (11/05/86)
I've wondered also... I think it (yawning) stimulates the tear ducts and cleanses the eye. BUT, why do we yawn if we see someone else yawn? .......chaz
dan@rna.UUCP (Dan Ts'o) (11/06/86)
In article <7841@tekecs.TEK.COM> mikes@tekecs.TEK.COM (Michael Sellers) writes: >Here's *my* side issue: I was recently asked why you yawn when you are >tired. I (somewhat smugly) replied that it was to get rid of excess Don't forget the socio-biology. Haven't you ever noticed that there is a great tendency others to yawn once someone in the same room yawn. It is a primate socio-behavioral signal for the colony to go to sleep at the same time.