Download Cells of the Small and Large Intestines

Cells of the Small and Large Intestines
Small Intestine Exocrine Function
The small intestine is primarily composed of simple columnar epithelial
cells with microvilli facing the lumen for absorption of digested
material. Intestinal crypts (also called the crypts of Lieberkühn) are
analogous to gastric glands of the stomach and are formed by
invaginations of the epithelium. Within the crypts are paneth cells, which
secrete multiple defensive proteins including lysozyme definsins and
phospholipase to protect the small intestine from pathogens which have
survived the stomach compartment. There are also Goblet cells, which
secrete mucous for protection from the acids of the stomach and
enzymes from accessory organs.
Small Intestine Endocrine Function
The small intestine also has enteroendocrine cells which secrete hormones
for regulation of absorption of nutrients. S cells produce secretin to
buffer intestinal pH. I cells (also called CCK cells) secretecholecystokinin,
which stimulates the release of digestive enzymes from the pancreas and
gall bladder in to the intestine. K cells secrete gastric inhibitory
peptide (GIP;
also
called glucose-­‐dependent insulinotropic peptide), which influences insulin levels
Cell Type
Location in the Mucosa
Function
Columnar
epithelium
with
microvilli
Lining
Digestion
and
absorption
of nutrients
in chyme
Goblet
Intestinal crypts
Secretion of
mucous
Paneth
Intestinal crypts
Secretion of
the
bactericidal
enzyme
lysozyme
and other
defensive
proteins;
phagocytosis
Enteroendo
crine
S cells
Intestinal glands
Secretion of
the hormone
secretin
I (or CCK)
cells
Intestinal glands
Secretion of
the hormone
cholecystoki
nin
K cells
Intestinal glands
Secretion of the
hormone gastric
inhibitory
peptide (GIP)
Large Intestine Exocrine Function
Most of the mucosa of the large intestine is composed of simple
columnar epithelial cells. An exception is the distal anal canal, which is
composed of nonkeratinized stratified squamous epithelial cells. The
stratified epithelium is more durable to the abrasion that occurs when
feces moves. The large intestine also has crypts, which contain both
epithelial cells and goblet cells. Since most digestion and absorption
occurs before the large intestine, the only significant secretion is mucus,
which lubricates the passage of digestive residue.