04 GI Tract

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Layers

• in all GI tract
• submucosa nerve plexus
• muscularis nerve plexus

Mucosa

• muscularis within epithelium

Submucosa

Muscular

• GI peristalsis
• achalasia: swallowing food problem

Serosa

• slippery

Esophagus

Stomach

• cardia: connection between esophagus/stomach. Epithelium changes from squamous to columnar

• lamina propria (arrow) between muscular layer (bottom) and epithelium (top)
• gastric glands: within lamina (circle)

• pink parietal cells near epithelium
• dark blue/purple G cell near bottom

Small intestine

• crypts: invagination

• muscular layer
• columnar epithelium

• only mucosa in villi
• goblet cell secretes mucous
• microvilli: can't see on light microscope

• increase surface areas
• both mucosa and submucosa

• M cell collect antigens and transmit to Peyer's patch (local lymph)

• white space left: lacteal

Colon

• goblet to produce lots of mucous

• dyspepsia: abd pain

Enteric Nervous

• auerbach between circular and longitudinal muscles

• muscle cells and not neurons
• regulate contractions

• neurons
• smooth muscle: resting state fluctuates