CHAPTER 15
Digestive Tract
303
Regions
Mucosa (Epithelium,
Lamina Propria,
Muscularis Mucosae)
Submucosa
(Submucosal
Plexuses Present
in this Layer)
Muscularis Externa
(Myenteric Plexuses
Present between
Smooth Muscle Layers)
Serosa/
Adventitia
Main Functions
Esophagus
Upper
esophagus
Nonkeratinized stratif ed
squamous
Esophageal glands
Inner circular and outer
longitudinal skeletal
muscles
Adventitia
Transport Food bolus
Middle
esophagus
Nonkeratinized stratif ed
squamous
Esophageal glands
Inner circular and outer
longitudinal mixed skeletal
and smooth muscles
Adventitia
Transport Food bolus
Lower
esophagus
Nonkeratinized stratif ed
squamous; esophageal
cardiac glands in lamina
propria
Esophageal glands
Inner circular and outer
longitudinal skeletal
muscles
Serosa
Transport Food bolus
Stomach
(
Rugae and Gastric Pits
)
Cardia
SurFace mucous cells
and gastric pits; mucus-
secreting cells oF cardiac
glands in lamina propria
No glands
Inner oblique, middle
circular, and outer
longitudinal smooth
muscles
Serosa
Add mucus and
lysozyme; churn Food
by peristalsis
±undus and
body
SurFace lining cells and
gastric pits; parietal
and chieF cells oF gastric
glands in lamina propria
No glands
Inner oblique, middle
circular, and outer
longitudinal smooth
muscles
Serosa
Same as above; add
acidic gastric juice (e.g.,
HCl, mucus, enzymes);
process Food into chyme
Pylorus
SurFace lining cells and
gastric pits; mucus-
secreting cells oF pyloric
glands in lamina propria
No glands
Inner oblique, middle
circular, and outer
longitudinal smooth
muscles
Serosa
Add mucus; churn
Food and pass chyme to
duodenum
Small Intestine
(
Villi and Crypts
)
Duodenum
Columnar absorptive
and goblet cells; Paneth,
enteroendocrine, goblet,
and absorptive cells in
glands (crypts) oF Lieberkühn
Brunner glands
Inner circular and outer
longitudinal smooth
muscles
Serosa/
adventitia
Allow bile and pancreatic
juice to enter small
intestine; release mucus;
regulate rate oF emptying
oF stomach; absorption
Jejunum
Similar to above
No glands
Inner circular and outer
longitudinal smooth
muscles
Serosa
Absorption oF
carbohydrates, proteins,
lipids, and vitamin K
Ileum
Similar to above with
increased goblet cells; Peyer
patches in lamina propria
Peyer patches may
extend into this
layer
Inner circular and outer
longitudinal smooth
muscles
Serosa
Similar to above;
absorption oF vitamins
K and B12 and bile salts
Large Intestine
(
Crypts, no Villi
)
Cecum/colon
Goblet cells and
columnar absorptive
cells; goblet, columnar,
and enteroendocrine cells
in glands oF Lieberkühn
No glands
Inner circular smooth
muscle; outer longitudinal
smooth muscle layer Forms
three teniae coli
Serosa/
adventitia
Absorption oF water
and electrolytes;
Formation oF Feces
Rectum
Similar to above; Fewer
glands oF Lieberkühn
No glands
Inner circular and outer
longitudinal smooth
muscles
Adventitia
Store Feces; sensory
receptors signal brain oF
the need to evacuate
Anal canal
Nonkeratinized to
keratinized stratif ed
squamous
Sebaceous glands
(distal portion);
venous
Inner circular (thickened to
become internal sphincter)
and thin outer longitudinal
smooth muscles
Adventitia
Internal sphincter and
external sphincter
(skeletal muscle); relax
to release Feces
TABLE 15-1
Digestive Tract
Note
: Simple columnar epithelium lines most oF the digestive tract, including the stomach and the small and large intestines. It does not line the
esophagus and the anal canal, however.
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