DIGESTIVE SYSTEM

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DIGESTIVE SYSTEM

• A Histological Study

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Layers of the Gut Wall
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Digestive Tract
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Layers of the Gastrointestinal Tract

• Mucosa
• Epithelium, CT, a little muscle
• Submucosa
• CT, glands
• Muscularis propria
• Muscles
• Serosa
• CT

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Mucosa

• Epithelium
• Differs with location, functions
• Lamina propria
• Loose CT, blood and lymph vessels
• Muscularis mucosae
• Thin layer with smooth muscle

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Protective epithelium (stratified squamous)
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Secretory
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Absorptive
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Absorptive/Protective
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SUBMUCOSA Loose/Dense irregular CT Supports
mucosa Contains large blood vessels, nerves,
lymphatics MUSCULARIS PROPRIA Two
layers Peristaltic contractions
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Wall of the Gut
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SEROSA/ADVENTITIA Loose CT Major vessels,
nerves, adipose
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TONGUE
Lingual tonsils
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Esophagus

• Muscular tube capable of pronounced peristaltic
  waves to propel food to stomach.
• Non-keratinized stratified squamous epith.
• Esophageal glands (mucus) in submucosa.
• Muscularis is striated muscle at proximal end,
  smooth muscle at distal end.
• Esophageal sphincter

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Esophagus
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Esophagus
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ESOPHAGUS x4
Lymphoid tissue
Lamina propria
Mucous gland
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ESOPHAGUS x10
MM LP
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Esophagogastric Junction
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Stomach

• Breaks down food by mechanical and chemical
  means.
• Churning, gastric juice
• Rugae
• Folds that permit distension of wall
• Regions
• Cardia, fundus, body, pylorus

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Regions of the Stomach
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STOMACH
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The Stomach
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Gastric Glands of Stomach
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STOMACH x10
LP MM
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GASTRIC GLAND
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Layers of the Stomach
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Stomach
Section of the gastric glands in the fundus of
the stomach. Note the superficial mucus-secreting
epithelium. Parietal cells (light-stained)
predominate in the mid and upper regions of the
glands chief (zymogenic) cells (dark-stained)
predominate in the lower region of the gland. MM,
muscularis mucosae.