eli5: how do stomachs keep things in them when you hang upside down?

Question

Say you drink a glass of water and then hang upside down. How does the stomach keep the water from traveling back up your esophagus?

In: 0

Answer 1

There is a sphincter between the esophagus and the stomach that normally stays closed unless you are swallowing something that needs to be passed into the stomach. This is called the gastroesophageal sphincter.

In a normal healthy human, this sphincter prevents things going from the stomach to the esophagus. Even when you are “hanging upside down”.

(If you don’t know what a sphincter is an example: your anus is a sphincter)