system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If you have microscopic tearing in the anal canal, why doesn’t your own faeces poison you?

Very small tears in the delicate anal tissue are apparently a common problem in humans, obviously more so in certain groups than others. Whether they’re microscopic or severe enough to cause bleeding, why doesn’t the faecal matter enter the blood stream and make you very ill? If you ate faeces you’d get gastroenteritis I assume, so wouldn’t faecal matter in the blood be really dangerous?
gpt
Large amounts of faecal matter in the blood can be very dangerous, but remember, the tear is microscopic, so only very small amounts get through. The body has a number of defense mechanisms once it detects disruption to blood vessels to prevent them from becoming contaminated.

Clots don't just help to stop bleeding, but also provide an extra boost of immune defense to help immediately shutdown any bugs that can get in.