Unit 5 Notes: The Small Intestine
(1) Regions• Duodenum: (First Chamber)–Approximately 10in long
• Jejunum: (Middle Section)–Approximately 7-8ft long
• Ileum: (Last Section)–Approximately 12ft long
(2) Inside the Duodenum• Secretes Bile, Pancreatic Juice & Bicarbonate:–Bile = Yellow-green solution produced by
the liver, stored in the gallbladder. –Pancreatic Juice = Solution produced by the
pancreas, stored in the pancreas.–Bicarbonate = pH balancing compound
found in the blood.
• Metabolize all remaining proteins and lipids.
(3) About Bile…• Produced by liver, Stored by Gallbladder• Contains:–Bile Salts–Waste Pigments (bilirubin)–Cholesterol & Phospholipids
• Function: Emulsify lipids so that they are dispersed throughout water, and can be easily absorbed.
(4) About Pancreatic Juice…• Produced by pancreas• Contains:–Carboxypeptidase (Protein Enzyme)–Chymotrypsin (Protein Enzyme)–Amylase (Carbohydrate Enzyme)– Lipases (Lipid Enzymes)–Nucleases (Nucleic Acid Enzymes)
• Function: Metabolize all remaining biomolecules.
(5) Releasing Bile & Pancreatic Juice
• Lipids & Proteins Release of CCK (cholecystokinin) into bloodstream
• CCK stimulates release of bile + pancreatic juice Out Sphincter of Oddi
(6) About Bicarbonate…• HCO3
• Used to maintain pH balance within cells (and water systems).–Neutralizes acidity of chyme coming
from stomach
• Secreted from Brunner’s Glands along Duodenum Walls.
(7) In The Jejunum & Ileum• Smooth Muscle with millions of microvilli:– Microvilli Absorb Nutrients– Nutrients directly deposited in blood stream– Folds in between are called “Crypts of Lieberkuhn”
• Crypts of Lieberkuhn:– Secrete Lysozymes to eliminate any foreign bacterial
cells– Secrete Muccin to lubricate and dissolve remaining
food stuff