•Hepatic sinusoids•Bile canaliculi•Hepatic triad– Artery– Vein–Bile ductule
Gallbladder•Concentrates and stores bile–Components of bile•Minerals, cholesterol, phospholipids, fats•Bile pigments–Bilirubin•Cystic duct–Hepatic duct–Bile duct•Enterohepatic circulation•Reabsorbed from SI to liver
Pancreas•Exocrine gland–Acinar cells•Zymogen granules•Enzymes, zymogens–Pancreatic duct•Sodium bicarbonate–Pancreatic juice
Bile and Pancreatic Juice Regulation•Neural–Parasympathetic (vagal) stimulation–Sympathetic inhibition•Hormonal–Gall bladder contraction and pancreatic secretion•Cholecystokinin (CCK)•Gastrin–Hepatic and pancreatic bicarbonate secretion•Secretin
Small Intestine•Chemical digestion and nutrient absorption• Duodenum– 1st25 cm (10 in)• Jejunum– Next 2.5 m (8 ft)• Ileum– Last 3.6 m (12 ft)
Microscopic Anatomy•Circular folds–Mucosa and submucosa–Force chyme to spiral through•Villi–Absorptive Cells (enterocytes)•Brush border of microvilli–Brush border enzymes–Goblet Cells–Lacteal–Intestinal crypts•Paneth cells•Duodenal glands–Bicarbonate-rich mucus
Intestinal Motility•Functions–Mix with intestinal juice, bile, pancreatic juice–Contact digestion and nutrient absorption–Move residue to LI•Segmentation–Mixing/contact digestion•Peristalsis–Migrating motor complex–Movement through SI
Chemical Digestion/Absorption•Digestion–Carbohydrates•Complex CHO to sugars–Proteins•Protein to AAs–Lipids•Fats to FAs and monoglycerides–Nucleic Acids•RNA and DNA into nucleotide monomers•Absorption–Completed when chyme reaches ileum–Ileum reclaims bile salts –End of ileum •remains some water, indigestable material, bacteria–Passed into large intestine
Carbohydrate Digestion•Mouth–Salivary amylase•Starch to oligosacchrides•Stomach–Churning, mixing–Inactivation of salivary amylase•Small Intestine–Pancreatic Amylase•Oligosacs to smaller oligosacs and Disacs–Dextrinase and Glucoamylase•Brush Border enzymes•Smaller oligosacs to Disacs–Maltase, Sucrase, Lactase•Brush Border enzymes•Disacs to Sacs
Carbohydrate Absorption•Glucose transported into absorptive cells–Sodium-Dependent Glucose Transporter (SGLT)•Secondary active transport coupled to sodium•Galactose–Uses SGLT as well•Fructose–Via facilitated diffusion–Converted into glucose•All transported to liver!!
Protein Digestion•Stomach–Pepsin •Peptide bonds •Tyrosine and phenylalanine•Polypeptides and AAs left•Small intestine–Pancreatic enzymes•Trypsin and chymotrypsin•Taken apart one AA at a time–Brush Border enzymes•Carboxypeptidase•Aminopeptidase•Dipeptidase
Protein Absorption•AA absorption similar to monosaccharides–
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- Spring '10
- Digestive System, salivary glands, muscularis externa, brush border, gastric secretions