Your appendix isn’t uselessThe appendix, that little wormlike thing that dangles off our large intestine, was once thought to be a mystery, a vestige of something in our evolutionary past. (Rabbits, for example, have a much larger intestinal pouch in that same area, which they use for digestion.)
It turns out that our appendix, far from being a useless lump of flesh, is full of tissues associated with the immune system. The current thinking is that it may serve as a backup storage site for our “good” gut bacteria, the better to replenish them after something like a bout of diarrhea.
Goosebumps are your skin trying to fluff up your body hair to keep you warm
Have you ever seen a bird on a cold day with its feathers all ruffled up, so it looks like a little puffball? Or a squirrel, doing much the same thing with its fur? That’s what your body is doing when you get goosebumps: Standing up each of your body hairs to better trap air underneath them to keep you warm.
It doesn’t work very well, of course, since we don’t have that much body hair. But if you look closely, you’ll notice that each goosebump is located at a hair follicle. There is actually a tiny muscle that contracts to pull the hair upright.
You only breathe through one nostril at a time
When you get a cold and have a stuffy nose, you may notice that only one nostril is stuffed up at a time, and which nostril that is changes throughout the day. That’s because we only breathe through one nostril at a time, even when we’re healthy. (The nostril that’s stuffed is just the one that happens to be resting at the moment.)
This is called the nasal cycle, and you can prove it to yourself by putting a hand under your nose. You’ll probably feel your breath more on one side than the other; if you feel it in both, you’ve caught the cycle during its transition. Wait a little while and feel again.
We have invisible stripes
Tiger stripes aren’t just for tigers; human skin has a similar stripey pattern. We just can’t usually see it.
Our stripes, called Blaschko lines, are formed as our cells are dividing and our body is growing in utero. These rows of cells, including skin cells, look identical and are thus not visible as stripes—most of the time. But certain rashes will follow the lines, making them visible, and sometimes they can be seen under powerful-enough ultraviolet light.
No comments:
Post a Comment