small intestines
duodenum (mixing bowl)
absorptive sections
jejunum
connects to the stomach (pyloric sphincter) and the jejunum (ligament of Treitz)
main location for digestive regulation
primary functions
neutralize: the acid from the stomach before it can damage the absorptive surfaces of the small intestines
regulate: GI tract activity by the release of hormones
recieve: chyme (highly acidic food soup) from the stomach and digestive enzymes from the pancreas
Brunner's glands: screte HCO3- ("local" alkaline juice)
these are located in the submucosa BELOW the muscularis mucosae
connected to the duodenum and the ileum
site of greatest absorption of nutrients in the small intestines
ileum
connected to the duodenum and the large intestine
cells
the jejunum has fewer goblet cells than the duodenum
goblet cells: basal nuceli, make mucus
microfold cells (M cells): located in the mucosal layer over Peyer's patches in the ileum, they endocytose antigens and transport them to underlying immune cells
entero-endocrine cells
paneth cells: located in the basal portion of intestinal crypts, very eosinophilic, produce lysozyme
small intestinal vili
ciliated simple columnar epithelium (cilia = microvili = brush border)
Peyer's patches
goblet cells
nerve
lacteal: lymphatic vessel of the small intestine, also absorb digested fat b/c its too big for capillaries
capillary network
nerve plexuses
Auerbach's plexus (myenteric) = regulates movement
Meissner's plexus (submucosal) = regulates secretion