DIGESTIVE SYSTEMDIGESTIVE SYSTEM

DIGESTIVE SYSTEMDIGESTIVE SYSTEM

A Histological Study

L f th G tLayers of the Gut WallWall

Digestive TractDigestive Tract

Layers of the GastrointestinalLayers of the Gastrointestinal Tract

• Mucosa– Epithelium, CT, a little muscle

• Submucosa– CT, glandsg

• Muscularis propria– Muscles

• Serosa– CT

MucosaEpithelium

Differs with location, functions,Lamina propria

Loose CT blood and lymphLoose CT, blood and lymph vessels

M l iMuscularis mucosaeThin layer with smooth muscle

Protective epithelium(stratified squamous)

Secretoryy

Absorptivep

Absorptive/Protective

SUBMUCOSA

Loose/Dense irregular CTLoose/Dense irregular CTSupports mucosaContains large blood vessels, nerves,Contains large blood vessels, nerves, lymphatics

MUSCULARIS PROPRIA

Two layersPeristaltic contractionsPeristaltic contractions

Wall of the GutWall of the Gut

SEROSA/ADVENTITIA

Loose CTMajor vessels nerves adiposeMajor vessels, nerves, adipose

TONGUETONGUE

Lingualtonsils

Esophagus

• Muscular tube capable of pronounced peristaltic waves to propel food to p p pstomach.

• Non-keratinized stratified squamousNon keratinized stratified squamous epith.

• Esophageal glands (mucus) in• Esophageal glands (mucus) in submucosa.M l i i t i t d l t• Muscularis is striated muscle at proximal end, smooth muscle at distal

d

Esophagus

Esophagus

ESOPHAGUS x4

Lymphoidtissue

Laminapropria

Mucousgland

ESOPHAGUSESOPHAGUS x10

MMMM

LP

Esophagogastric p g gJunction

Stomach

• Breaks down food by mechanical and chemical means.– Churning, gastric juice

• RugaeRugae– Folds that permit distension of wall

Regions• Regions– Cardia, fundus, body, pylorus

Regions of the Stomach

STOMACH

The StomachThe Stomach

Gastric Glands of SStomach

STOMACH x10LP MM

GASTRIC GLANDGASTRIC GLAND

Layers of the Stomach

StomachStomachSection of the gastric glands in the fundus of thein the fundus of the stomach. Note the superficial mucus-secreting epithelium. Parietal cells (light-stained) predominate in the mid and upperin the mid and upper regions of the glands; chief (zymogenic) cells (dark-stained) predominate in thestained) predominate in the lower region of the gland. MM, muscularis mucosae.

SMALL INTESTINE

• Plicae circularis• VillusVillus• Enterocyte

B h b d ( i illi)• Brush border (microvilli)• Crypts of Lieberkuhn• Brunner glands (Duodenum)• Peyer’s patchesPeyer s patches

DUODENUM

GASTRODUODEMAL JUNCTION

SMALL INTESTINE

PlicaPlicacircularis

Plica Circularis

Duodenum x20

Small Intestine x2

Small Int Brunner’s Gland x40

Villus

Goblet cells

Intestinal glands(Crypts of Lie-Berkuhn)

Crypts containPaneth cellsPaneth cells (alkaline mucusSecretion)Secretion)

VillusVillus

Crypt

VillusVillus

VILLUS

ENTEROCYTESENTEROCYTES

Small Int Ileum Circularis x2Small Int Ileum Circularis x2

Small Int x10

SI Crypts x20

SI Ileum Peyer’s Patch x4

The Colon

• Mucosa with crypts (glands)• Glands consist of absorptive cells andGlands consist of absorptive cells and

mucus secreting cells• Muscularis propria is very pronounced• Muscularis propria is very pronounced• Longitudinal muscle occurs in 3 bands

(t i li) th th l t l(taeniae coli) rather than completely surrounding tract.

COLON

COLON x2

Large Int GALT x4Large Int GALT x4 (Gut associated lymphoid tissue)

Colon Crypts x10

Large Int Crypts cx x20

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