Significant-Offer-71 t1_j67bdf5 wrote on January 28, 2023 at 5:48 AM

Reply to comment by WordsNumbersAndStats in Eli5: how does stomach acid not exit with feces when we have diarrhoea? Isn't it just a sphincter which should in theory not be infallible? by Thtanilaw1113

The “sphincters” are all valves, they don’t care what goes through. They aren’t there to keep stomach acid from passing. The reason stomach acids don’t make it to your poop is the reason stated above. Acid gets neutralized as soon as you hit the duodenum. Digestion is extremely complex. By the time food reaches the rectum, it’s gone through 15+ feet of tubing and several complex chemical reaction to be come the substance we all know and love.. poop