Learning is Fun!

Last semester was pretty much balls. We didn't get to choose our classes, and we had constant tests. None of it was fun in any way, because even the few things that would have been awesome to learn were just more weights being added onto our backs come test time.

This semester is a bit different, however. We will have 12 one-hour credit classes that each last 5 weeks, and are only made up of ten lectures. We had choices (although it was only 2-3 choices per time block, but that's better than nothing!). There was an element of control for us this semester, and we will only have tests every 5 weeks instead of every other week.

So, there are actually parts to this semester so far that have been really interesting, and even at times (gasp!) fun. So, I thought I'd tell you a little about what I'm learning tonight in my reading for my Genes to Physiology class tomorrow.

The reason that you feel lightheaded when you stand up is that the weight of all that blood in your body kind of sends it all crashing down to your legs, and there are nerves near your carotid arteries that recognize this and quickly work to make up for this difference by increasing your blood volume for a short time. This weight is why your feet swell and hurt--because of blood pooling, and to keep this from happening too much (and to keep from fainting if you lock your knees for too long), you need to occasionally contract and release your leg muscles a few times to cause the pooled blood to go back to your heart. Also, if you faint after giving blood it has absolutely nothing to do with your blood volume--it has only to do with the emotional center of your brain. So, no matter what anyone says, if they faint from giving blood it is because they are a wimp.

Oh, and if someone faints, you shouldn't try to get them upright! They fainted because of less blood going to the brain, so keeping them horizontal is what helps the most.

After a large loss of blood, the first mechanism that happens is something called autotransfusion, which basically means that your body takes interstitial fluid and adds it to your bloodstream, which dilutes out all the blood cells but keeps your mean arterial pressure more constant. Then you can slowly start to make more blood cells to replenish that shizz.

Weight training too much is bad for your heart!! What happens when you are lifting like that is that your heart starts trying to get more blood to these muscles, but the contraction is forcing the blood vessels more closed, and the extra blood isn't able to force its way in there. If you do this too much without rest or at least some good cardio thrown in there, it starts causing it causes hypertrophy of your left ventricle wall and lower volume in that chamber.

Ok, hopefully that was actually interesting to you, and if not, fuck off. Or, read this bit of depressing news:

More heart disease!