Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

C h a p t e r
THE DIGESTIVE
SYSTEM
The digestive tract begins at the mouth and ends at the anus. The lips, teeth,
tongue, salivary glands, mouth, and pharynx are considered in other chapters
of this book. The remaining digestive tract organs are the esophagus, stomach,
duodenum (the first part of the small intestine), jejunum and ileum (also
parts of the small intestine), colon, rectum, and anus. The organs that aid in
digesting and absorbing foodstuffs are the pancreas, gall bladder, and liver.
The pancreas is located next to the duodenum. The pancreatic enzymes drain
into the pancreatic duct, which joins the bile duct from the liver; both ducts
empty into the duodenum.
The esophagus is a muscular tube that carries food down to the stomach
through a series of rhythmic contractions. The esophagus runs along the neck
and into and through the chest cavity, on its way to the stomach. The lower
esophagus enters the stomach at a sharp angle, which prevents food and liquids
from refluxing back up into the esophagus.
Food can remain in the stomach for up to eight hours before passing
through the pylorus into the duodenum and rest of the small intestine.
Digestive juices from the pancreas and small intestine break the food down
into amino acids, fatty acids, and carbohydrates. The products of the meal are
absorbed into the intestinal circulation and are carried to the liver, where
they are converted to stored energy.
Fiber and undigested food continue on through the small intestine into the
colon. The function of the colon is to remove water and store waste material
as feces.
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