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Digestive System

If you eat salmon for dinner, what happens to the food after you swallow? Your digestive system’s role is to extract nutrients from food you eat and excrete what is left over.

The first step in digestion is chewing up your food and swallowing it down your esophagus into your stomach. Your stomach contains acid and enzymes, molecules that can break down particles of food. After a while, the partially digested food leaves the stomach and enters the small intestine. There, chemicals from your liver and gall bladder break down other food particles. In the small and large intestines, nutrients are absorbed through the intestine walls and enter the bloodstream or lymph. The parts of the food that cannot be absorbed by your body move through your intestines and are eventually excreted through the anus.

It takes many hours for food to move through your intestines – your body is trying to get as many nutrients as possible from your food! Food moves through your digestive system by the contractions of smooth muscle that line the whole pathway.

Written using information from the NIH National Cancer Institute and the NIH National Institute of Diabetes and Digestive and Kidney Diseases.

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