Digestion - Proteins Flashcards
1
Q
Event in the oral cavity
A
None
2
Q
Event in the stomach
A
- HCl secreted by parietal cell converts pepsinogen to pepsin
- Pepsin digests dietary proteins to release peptides and a few amino acids
3
Q
Event in the small intestines
A
- Most proteins and oligopeptides are digested by pancreatic enzymes (specific)
- Enteropeptidase activates trypsinogen, and trypsin is capable of activating all the rest, including itself
- Aminopeptidase located on the brush border and release free amino acids from dipeptides and oligopeptide
4
Q
How are protein molecules absorbed in the small intestines?
A
- Free amino acids are absorbed via secondary active transport, coupled with Na+
- Di- and tripeptides are absorbed by a H+-linked transport system
5
Q
How are protein molecules exported out of the small intestines?
A
Free amino acids are taken to the portal circulation via facilitated diffusion out of the enterocyte
Summary:
- Into the enterocytes - Secondary active transport
- Out of the enterocytes - Facilitated diffusion
6
Q
Proteolytic enzymes of digestion is can activate other proenzymes of protein digestion
- Enzyme
- How activated
A
- Enzyme
- Trypsin
- How activated
- Enteropeptidase activates trypsinogen
