Structure and Innervation of the GI Tract

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🌱 來自: Huppert’s Notes

Structure and Innervation of the GI Tract🚧 施工中

Structure and Innervation of the GI Tract

•   Components: The GI tract includes epithelial cells (specialized for absorption/secretion), muscularis mucosa (changes surface area for absorption/secretion), circular muscle (decreases the diameter of the lumen), and longitudinal muscle (shortens a segment of the GI tract)

•   Extrinsic innervation: May be parasympathetic (excitatory, via the vagus/pelvic nerve) or sympathetic (usually inhibitory)

•   Intrinsic innervation: Coordinates extrinsic signals and uses local GI reflexes to modify motility (via the myenteric plexus) and secretion/blood flow (via the submucosal plexus)

FIGURE 4.1: Anatomy of the gastrointestinal tract.

FIGURE 4.2: Locations and functions of the GI secretory cells. The secretory cells are indicated in blue and their secreted hormone products are shown with arrows and indicated in black. Abbreviations: Acetylcholine (Ach), hydrochloric acid (HCl), enterochromaffin-like (ECL), gastrin-releasing peptide (GRP), gastric inhibitory polypeptide (GIP), cholecystokinin (CCK), gastrin cells (G cells), delta cells (D cells).