Notes: Small Intestine

Wednesday 1-6-10

(1) Overall Function

Absorb nutrients from stomach chyme

Metabolize ALL Proteins and Lipids

Leave only waste and water

(2) Regions

Duodenum: (First Chamber)– Approximately 10in long

Jejunum: (Middle Section)– Approximately 7-8ft long

Ileum: (Last Section)– Approximately 12ft long

(3) 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.

(4) 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.

(5) 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.

(6) Bile & Pancreatic Juice Secretion

Lipids & Proteins Release of CCK (cholecystokinin) into bloodstream

CCK stimulates release of bile + pancreatic juice Out Sphincter of Oddi

(7) 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.

(8) Jejunum

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

(9) Ileum

Smooth muscle like Jejunum:– Contains Microvilli– Absorbs all left over nutrients– Directly deposits into bloodstream

Remaining “stuff” = waste