Digestion in the Small Intestine

The Small Intestine

• The small intestine has an opening from the bile duct and pancreatic duct, allowing bile and pancreatic enzymes to enter.

Digestion in the Small Intestine

• Chyme, a semi-solid mixture of food, enters the small intestine and is acidic due to HCl from the stomach.
• The presence of chyme triggers the conversion of prosecretin to secretin, which is absorbed into the bloodstream and carried to the pancreas.
• Secretin is necessary to neutralize the acidic chyme.

Large Intestine

• The large intestine is approximately 5 feet long.
• It accepts the remaining nutrients not absorbed by the small intestine.
• The rectum provides short-term storage for feces before it is expelled.

Anus

• The anus is the external opening of the rectum.
• Sphincter muscles control the closure of the anus.
• Feces are expelled from the body through the anus during defecation.

Pancreas and Carbohydrate Digestion

• Amylase enzymes from the pancreas break down large carbohydrate chains into disaccharides.
• Disaccharide enzymes from the small intestine then break down disaccharides into individual sugars.

Pancreas and Protein Digestion

• Trypsinogen, a protein-digesting enzyme, is released into the small intestine and converted into trypsin.
• Trypsin breaks down large protein chains into smaller chains.
• Erepsins from the pancreas then break down smaller chains into individual amino acids.