Digestive glands Flashcards
Origin of digestive glands
Endoderm -> Gut tube epithelium
Three salivary glands + characteristics
Parotid - purely serous
Submandibular - mostly serous, some mucous
Sublingual - mostly mucous, some serous
- Serous cells in demilune when both are present (mucous takes over middle of the acinus)
Overall histology of salivary gland
Acini with secretory cells and contractile myoepithelial Intralobar ducts - intercalated (simple squam or cub) -> striated (simple column) Interlobar ducts (pseudostratified->strat column)
Striated ducts
Larger intralobar
Simple columnar
Infolding of basement membrane with lots of mitochondria (-> pink striations)
Ion transport, secretes lysozyme, transports IgA from plasma cells
Functions and content of saliva
Lubrication - water and glycoproteins (mucous)
Digestive - alpha-amylase -> carbohydrates
Immune - IgA, lysozyme
Protective - pellicles -> protein film
Approoox 1500 cc/d
Functions/secretions of pancreas
All serous
Digestive enzymes - amylase, lipase, trypsinogen, ribonuclease
- controlled by cholecystokinin
Ions - mostly bicarb - buffers gastric acid and allows activation of enzymes
- controlled by secretin
Histology of pancreas
All serous
No striated ducts, intercalated less obvious
No myoepithelial cells
Centroacinar cells - ducts inside lumen - release bicarb
Functions of liver
Protein synthesis - clotting factors, albumin
Bile metabolism - bilirubin, phospholipids, cholesterol
Detox/inactivation - oxidation, methylation, conjugation
Storage - lipids -> triglycerids, carbs -> glycogen
Gluconeogenesis
Classic liver lobule histology
Portal triad peripheral - hepatic artery, portal vein, bile duct
Blood flows through sinusoids -> central vein in middle
Hepatocytes line sinusoids, send bile -> canaliculi -> terminal ductule -> bile duct in triad
Hepatic sinusoids
Carry mixed blood from hepatic artery and portal vein
Large, discontinuous capillaries (incomplete basement, large fenestrations) to facilitate transport
Thin perisinusoidal space (of Disse) between basement and hepatocytes (many microvilli)
Flows from triad to central vein
Portal triad
Bile duct branch - identify via simple cuboidal epithelium!
Hepatic artery
Portal vein (blood mixes into sinusoids)
Kuppfer cells
Local macrophages in liver
Localized to internal endothelium of sinusoids
Ito cells
Vitamin A storage
Local immunity
Localized to perisinusoidal space (of Disse)
Hepatocyte organization
Organized into plates along sinusoids
Microvilli along basal surface (in perisinusoidal space) - both absorption and secretion
Lateral domain - tight junctions with neighboring hepatocytes
Bile exocytosis through small apical surface into bile canaliculi (sealed by tight junctions)
Usually have multiple domains - labelled for what they are bordering!
Bile flow
Opposite of blood flow!
Bile canaliculi (between hepatocytes) ->
terminal duct (choleagiole, canals of Hering) ->
bile duct branch in triad