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