Anatomy Unit 3 Notes: The Small Intestine

1. Unit 3 Notes:
The Small Intestine

3. (1) Regions
• Duodenum: (First Chamber)
–Approximately 10in long
• Jejunum: (Middle Section)
–Approximately 7-8ft long
• Ileum: (Last Section)
–Approximately 12ft long

5. (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.

6. (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.

8. (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.

9. (5) Releasing Bile & Pancreatic Juice
• The presence of Lipids & Proteins 
Release of CCK (cholecystokinin) into
bloodstream.
• CCK stimulates the release of bile + pancreatic
juice out Sphincter of Oddi.

11. (6) About Bicarbonate…
• 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.

12. (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.