When food is swallows, food pushes into
the esophagus, the muscular tube that carries food and liquids from the
mouth to the stomach. swallowing begins, it becomes involuntary and
proceeds under the control of the esophagus and brain. The lower
esophageal sphincter, a ringlike muscle at the junction of the esophagus
and stomach, controls the passage of food and liquid between the
esophagus and stomach. As food approaches the closed sphincter, the
muscle relaxes and lets food pass through to the stomach.
The stomach stores swallowed food and
liquid, mixes the food and liquid with digestive juice it produces, and
slowly empties its contents, called chyme, into the small intestine. The
muscle of the upper part of the stomach relaxes to accept large volumes
of swallowed material from the esophagus. The muscle of the lower part
of the stomach mixes the food and liquid with digestive juice.
The muscles of the small intestine
mix food with digestive juices from the pancreas, liver, and intestine
and push the mixture forward to help with further digestion. The walls
of the small intestine absorb the digested nutrients into the
bloodstream. The blood delivers the nutrients to the rest of the body.
The waste products of the digestive
process include undigested parts of food and older cells from the GI
tract lining. Muscles push these waste products into the large
May 4th, 2015
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