AMA 172 - Anatomy &
Physiology/Medical
Terminology/Pathology 3
Digestive System
Digestive system (gastrointestinal)

Starts with
mouth, food
enters,
passes
through
stomach and
intestinal
tract and
ends with
anus where
waste leaves
3 functions:






Digestion:
food taken in and broken down mechanically by chewing and
chemically by digestive enzymes
Absorption:
Nutrients from food (sugar, fatty acids & amino acids), enter
bloodstream via the walls of the small intestine and go to all
cells of the body
Cells burn (catabolize) nutrients, in presence of oxygen, to
release energy
Cells use amino acids to build (anabolize) large protein molecules
for growth and development
Elimination:
solid waste materials that cannot be absorbed are concentrated
(feces) in the large intestine and pass out of the body
Anatomy of the digestive
system:



Oral Cavity: cheeks, lips, hard palate, soft palate, rugae, uvula,
tongue, papillae, tonsils, gums, teeth, salivary glands
Mastication (chewing) and deglutition (swallowing) break down
and move food to the stomach via the esophagus. Salivary glands
produce saliva that contains digestive enzymes that help break
down food.
Pharynx: also called the throat, is a muscular tube or
passageway for food to pass through the esophagus (and air to
the trachea). When you swallow, a flap called the epiglottis
covers the trachea so food does not enter the windpipe
Anatomy of the digestive
system continued:


Esophagus: a muscular tube that connects the
pharynx to the stomach. Involuntary rhythmic
muscular contractions called parastalsis, move
the food down to the stomach
Stomach: contains enzymes and acid to
prepare food for the intestine. Sphincters
control the openings into (cardiac sphincter)
and out of (pyloric sphincter) the stomach.
Digestion takes about 1 to 4 hours.
Anatomy of the digestive
system continued:
Small Intestine: called the small bowel,
extends about 20 feet. Contains villi
(microscopic projections) that absorb
nutrients into the bloodstream
 Large Intestine: called the large bowel,
receives the waste products of
digestion, absorbs most of the water
from the waste and expels the waste in
solid stools (feces)

Anatomy of the digestive
system continued:



Liver, Gallbladder, Pancreas: additional
organs of digestion. Liver manufactures bile,
the gallbladder stores it and the pancreas
secretes digestive enzymes
Liver: produces bile, maintains normal glucose
levels, manufactures blood proteins
(especially for clotting), releases bilirubin and
removes poisons from the body
Pancreas: secretes enzymes to digest fat and
insulin that carries glucose into the cells to be
used for energy.