04 GI Tract

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