How does our stomach know which food should be passed on to the intestine and which should still remain there for digestion?

Question

Assuming I eat some food which needs 4 hours of digestion in the stomach. 3 hours and 55 minutes later I eat something else which can get more easily digested but still needs, let‘s say 1 hour, of digestion. How does our stomach know what to pass on and what to keep?

In: 5

Answer 1

The stomach doesn’t know anything. It’s more or less like a bag of digestive juices with an opening at the bottom and the time food spends in the stomach is determined by how long it takes to go down that hole (into the small intestine). It’s about how liquid the food is and how backed up the initial section of the small intestine is. Food flow though the intestine is usually pretty steady unless there’s a blockage or something happens that triggers the body to evacuate it.