Large Intestine
Functions of the large intestine
• Absorption of water and some vitamins
• Formation of feces
Parts of the large intestine
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Cecum
Colon
Rectum
Anus
Cecum
• Cecum begins at the ileo-cecal valve
• The cecum is 6cm (2.5 inches) in length.
• The appendix hangs off of the cecum.
Colon
• The colon makes up the bulk of the large
intestine, over 90% of the large intestine is
the colon
• The colon is divided into four distinct
regions. Ascending, transverse,
descending, and sigmoid.
Rectum and anal canal
• The rectum is 20 cm (8 in)
• The anus the final 2-3 cm (1 in) of the
alimentary canal. It terminates at the
exterior end the anus.
• Two sphincter muscles are found here.
The internal anal sphincter is involuntary
(smooth muscle), while the external anal
sphincter (skeletal muscle)
Absorption and feces formation
• Chyme remains in the large intestine 3-10
hours. By now it is called feces.
• Feces is composed of water, inorganic
salts, sloughed off epithelial cells, bacteria,
products of bacterial decomposition, and
undigested parts of food.
• Water is absorbed by the large intestine.
Fiber
• Fiber is indigestible plant substance. It
creates bulk in your large intestine. This
bulk helps with the peristaltic wave.
• People who choose a fiber rich diet reduce
their risk of obesity, diabetes,
atherosclerosis, gall stones, hemorrhoids,
diverticulitis, appendicitis, and colon
cancer
Diarrhea and constipation
• Diarrhea – food moves to fast through the
small intestine, and there is too much
water in the chyme, and the large intestine
cannot absorb enough water out, leaving
chyme (feces) with too much liquid.
• Diarrhea is treated with fiber rich
substances to create more solid materials
in the LI
Constipation
• Constipation is defined as infrequent or
difficult defecation.
• Too much water is absorbed by both the
large and small intestine. The feces
becomes dry and hard, making it difficult
to pass.
• Laxatives induce defecation, thus can be a
short term treatment.