23 14-18 Flashcards
Small intestine adaptations
- Circular folds/plicae circulares
- Villi
- Microvilli
- Blood capillaries (pick up H2O based nutrients)
- Lacteals (absorb lipids)
- Length of intestine
- GALT (immunity)
Gross anatomy of small intestine
Pyloric sphincter - Duodenum 10” - Jejunum 8’ - Ileum 12’ - Ileocecal valve Has accesory organs: Liver, gallbladder, pancreas
Micro anatomy of small intestine
Highly adapted for absorption: Plicae circulare/villi/microvilli.
Simple columnar absorptive cells with tight junctions and goblet cells.
Intestinal crypts/crypts of lieberkuhn intestinal crypt cells (secrete intestinal juice that serves as a carrier fluid for absorbing nutrients from chyme.)
Enteroendocrine cells/enterogastrones secretin-CCK.
Intraepithelial lymphocytes,
Paneth cells (defensins/lysozyme),
Peyer’s patches/GALT - these three are immune cells.
Duodenal glands in submucosa - secrete alkaline mucus
Small intestine function
complete digestion, most of absorption, protection/immunity
What type of cells are in the intestinal crypts?
Crypt epithelial - secrete intestinal juice, a watery mixture that contains mucus and is a carrier fluid.
Enteroendocrine cells - secretin, cholecystokinin.
IELs - intraepithelial cells that are T cells.
Paneth cells are deep in the crypt – defensins/lysozyme
How much saliva per day? Stomach juice? Intestinal juice?
1.5, 2L, 1-2L slightly alkaline
Function of liver
Protein synthesis (albumin/fibrinogen/alpha-beta globulins/hepcidin) Urea synthesis Storage (2 hrs glycogen) Hormones (EPO/TPO/angiotensinogen/IGF) Detox (#1 goal) Ooooox Glucose and fat metabolism
Bile formation
Liver role in digestion
Synthesis and secretion of bile - bile acts like a detergent, breaks fat into smaller pieces
What is bile?
Mostly water with some ions, bilirubin, cholesterol and lipids know as bile salts.
Special cells in the liver?
Kupffer - phagocytes and APCs
Embedded in sinusoid walls
Liver anatomy
3.5 lbs, hepatocytes, sinusoids, L/R lobes, falciform ligament (attaches ventrally).
Blood supply is hepatic artery, hepatic portal vein
Enzymes?
Mouth: salivary amylase, lingual lipase
Stomach: pepsin, gastric lipase
Small intestine: pancreatic amylase, trypsin, chymotrypsin, pancreatic lipase
Brush border: dexrinase, glucoamylase, amylase, lactase, maltase, sucrase, aminopesidase, carboxype
gallbladder anatomy and function
4” long, thin walled muscular sac.
Inferior surface of R lobe of liver
Concentrates bile by absorbing water and ions.
Honeycomb folds that allow it to expand.
Expels bile out of cystic duct –> bile duct.
Regulation of bile and pancreatic secretion and entry into small intestine. 6 steps
- Entrance of chyme into duodenum causes the release of CCK and secretin from duodenal enteroendicrine cells.
- CCK/secretin enter bloodstream.
- CCK induces secretion of enzyme rich pancreatic juice. Secretin causes secretion of HCO3- rich pancreatic juice.
- Bile salts (major stimulus) and some secretin stimulate liver to produce bile more rapidly.
- CCK (via bloodstream) causes gallbladder to contract and hepatopancreatic sphincter to relax; bile enters duodenum.
- During cephalic and gatric phases, vagal nerve stimulation causes weak contraction of gallbladder.
Secretin
Causes HCO3- secretion from pancreas.
Targets liver to ↑ bile production.
