Human BodyDigestion
Most of your serotonin is made in the gut, not the brain — and it cannot cross into the brain from there.
The two supplies are chemically identical and completely separate.
Source
This fact is written from the English Wikipedia article it links to, so you can check every word in one tap. Fact Drop rates that source 4 out of 5 for credibility, and the rating travels with the fact on the back of its card in the app.
More human body facts
Human body facts about the one you are sitting in. Roughly 8% of your DNA came from ancient viruses, you almost certainly have mites living on your face, and a newborn can breathe and swallow at the same time. Every fact links to the reference behind it.
- Your stomach acid can dissolve a razor blade.
- Your gut runs on its own nerve network of several hundred million neurons, roughly what a cat carries in its whole brain.
- Your appendix is not useless.
- Roughly 8% of human DNA came from ancient viruses.
- Cells cross the placenta in both directions during pregnancy.
- Across mammals, a lifetime works out at roughly a billion heartbeats whether you are a shrew or an elephant.