The Mouth This is where the digestive process begins. Saliva also activates our taste buds. If we didn't have saliva, we wouldn't be able to taste anything. Food gets pushed down in waves called peristalsis. This only takes a few seconds.
Peristalsis works all through the digestive system.
To show how it works, put a tennis ball in the top of a long sock. Hold one hand at the top of the sock and squeeze the ball down a bit, then get your other hand and place it under the first and squeeze it down further and so on. This happens so food can still move if we are hanging upside-down, lying down or even in space where there is no gravity. Here the food gets broken down and mixed and churned with some more digestive juices for about 2 - 4 hours until it turns into a thick soupy liquid. When you vomit, the food comes from the stomach.