How Is Food Digested?
When you take a bite of food, saliva pours into your mouth from nearby glands and mixes with the food as you chew. When you swallow, the food moves into your stomach, and is churned and mixed with gastric juices. The food passes into a long tube called the small intestine, and is further broken down by the body’s digestive juices.
In the small intestine, the nutrients in the digested food are absorbed into the blood and carried to all your cells. The parts of the food your body can’t use go into a tube called the large intestine, and then out of your body.
Your large intestine is also sometimes called the colon. Think of this area as a giant sponge and press whose only jobs are to absorb water from the mass you deliver to it and then squeeze the dry leftovers into compact bundles of waste — which you may know as feces.
After resident colonies of friendly bacteria digest any amino acids remaining in the waste and excrete smelly nitrogen — in a process scientists call passing gas — muscular contractions in the rectum push the feces out of your body, and digestion is finally done.
Digestion is the process of changing food into a form that the body can absorb and use as energy or as the raw materials to repair and build new tissue. Digesting food is a two-part process that’s half mechanical, half chemical.
Mechanical digestion begins in your mouth as your teeth tear and grind food into small bits and pieces you can swallow without choking. The muscular walls of your esophagus, stomach, and intestines continue mechanical digestion, pushing the food along, churning and breaking it into smaller particles.
Chemical digestion occurs at every point in the digestive system, beginning when you see or smell food. These sensory events set off nerve impulses from your eyes and nose that trigger the release of enzymes and other substances that will eventually break down food to release the nutrients inside. The body then burns these nutrients for energy or uses them to build new tissues and body parts.