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