1. Unit 2: Digestion in The Small Intestine

2. (1) Small Intestine Regions
First Chamber = Duodenum (~10in long)
Second Chamber = Jejunum (~7-8ft long)
Third Chamber = Ileum (~12ft long)

4. (2) The Duodenum
The duodenum contains a solution used to metabolize any remaining biomolecules from the stomach.\
The solution contains: Bile, Pancreatic Juice and Bicarbonate.

6. (3) Bile
Bile is a yellow-green solution produced by the liver, and stored in the gallbladder.
Bile contains salt compounds, lipids, and waste pigments from blood cells.
The function of bile is to emulsify lipids for better absorption…
Lipids form micelles since they are polarized molecules.
Bile helps break apart the micelles into individual lipids.
This allows our bodies to more easily absorb them.

8. (4) Pancreatic Juice
Pancreatic Juice is produced by and stored in the Pancreas.
Contains:
Carboxypeptidase and Chymotrypsin enzymes for metabolizing protein.
Amylase enzyme for further carbohydrate metabolism.
Lipase enzymes for lipid metabolism.
Nuclease enzymes for nucleic acid metabolism.

9. (5) Releasing Bile & Pancreatic Juice
The presence of metabolized proteins and lipids in the duodenum triggers the release of CCK (Cholecystokinin) into the blood stream.
CCK stimulates the release of bile and pancreatic juice into the duodenum.
The solutions secrete out of an opening called the “Sphincter Oddi”.

11. (6) Bicarbonate
Bicarbonate is a compound which balances out a solution’s pH by absorbing and releasing hydrogen ions.
The chyme that leaves the stomach is extremely acidic.
Bicarbonate neutralizes the low pH.
Bicarbonate is secreted from glands in the duodenum called “Brunner’s Glands”.

13. (7) The Jejunum & Ileum
Used to absorb all nutrients from food and liquid.
Both contain microvilli:
Microvilli are small finger-like projections used to absorb nutrients.
They are directly connected to capillaries and the blood stream.
Folds in between the microvilli are called the “Crypts of Lieberkuhn”:
These folds secrete Lysozymes to kill bacterial cells.
The folds also secrete Muccin to further lubricate food.