Important Differences in the Layers of the Alimentary Tract
Area of GI Tract
Esophagus
Stomach
Small Intestine
Mucosa
Stratified columnar
epithelium
Rugae folds, gastric pits
between folds, gastric
glands/parietal cells below
colum. epith. make HCl:
chief cells make zymogen
enzymes; lamina propria at
base of mucosa (superficial
to submucosa); goblet cells
make mucus
Villi, microvilli on
columnar epithelium;
brush border enzymes
made by columnar cells;
goblet cells make mucus
here; deep crypts between
villi; bounded on deep
surface by lamina propria;
Duodenum Heavy villi folds, found in
retroperitoneal position
Illeum Less elaborate villi
Large intestine
Great numbers of goblet
cells, no villi but still has
crypts; lamina propria at
base
Submucosa
Muscularis mucosa most
superficially, going deep to
connective tissue
Muscularis
Some skeletal muscle with
smooth muscle
3 smooth muscle layers:
oblique (for mixing),
circular, longitudinal for
squeezing
Serosa
Serosa is called aventitia
in thoracic cavity
Serosa also called
visceral periotoneum
2 smooth muscle layers:
longitudinal and circular
layers; no oblique layer.
Serosa also called
visceral periotoneum
2 major layers; longitud.
layer reduced to 3
sublayers called tenae coli;
circular layer also;reduced
longit. muscle creating
puffy haustra
Serosa also called
visceral periotoneum;
fatty eplipoic
appendages hang from
visceral peritoneum
Duodenal/Brunner's glands
evident
Peyer's patches in
submucosa, increasing in
number distally