The most medical, polite, and unemotional way to talk about poop is to call it stool or a bowel movement—BM for short.
My apologies to anyone whose initials are BM. I’m sure your parents meant well. At least your name isn’t Harry Bear or Shanda Leer. No joke. I’ve met these people.
Bowels are your intestines--a windy canal of fun and excitement. All your food takes a mystical journey from your stomach to the small intestine, the large intestine, the colon, and finally the rectum.
When food leaves the stomach and enters the small intestine, it is further broken down so that nutrients—protein, fat, carbohydrate, and some vitamins—can be extracted. Bile, a mixture of acids and salts, is added to the mix to help with this absorption. One ingredient of bile, bilirubin, is a product of red blood cell breakdown, and this is what gives fecal matter its lovely brown hue.
The small intestine has 3 regions: the duodenum is the first 10 inches of the small intestine, the jejunum is the next couple feet, and the ileum is twice as long as the jejunum. Don’t the names sound like Tolkien characters?
The entire small intestine is about 19' (6m) long. That's about the height of a giraffe.
In the large intestine, water is extracted from the mass to form a lovely solid poop. The end of the large intestine is the colon—the lounge where the poop hangs out and water continues to be removed.
When the poop is fully rested, it makes its way to the last stop of its epic journey, the rectum. Pressure signals in the walls of the rectum alert you that it’s time to go. If you fail to drop the payload within a few minutes, the poop retreats to the colon to resume lounging. But while it waits, more water is removed, so if you continually fail to let the poop see the world, you may end up with a poop that’s difficult to pass.
When you’re finally ready to let the poop be free, you engage your sphincter muscles. There are two: one for pushing out, one for holding in. For the love of Pete, don't get them confused.
Congratulations! You have now successfully pooped, in a toilet no less. Yes, I know. It does smell. That’s because of the intestinal bacteria and their waste products that make up about 8% of the mass of your poop. It’s a great way to remind us that we should stay away from it.
Here is a poop chart (a new kind of pie chart) of the makeup of feces.
Now, if you’ll excuse me, I have to drop the kids off at the pool.