Digestion & Absorption Flashcards
Lingual lipase
Mixes with food in mouth but carries out its action in stomach; targets short to medium chain FA
Salivary amylase
alpha(1-4) bond break down of starch & glycogen
Pepsin
Protein digestion; HCl activates pepsinogen; further activation via autocatalysis
Gastric lipase
Short to Medium-chain FA; Imp. for FA in milk digestion for neonates; also imp. in people who lack pancreatic lipases
Gastrin
Stimulates gastric secretions (HCl & pepsinogen) and gastric emptying
Secretin
Secretin release stimulated by chyme; stimulates pancreas to release bicarb
CCK
CCK release by enteroendocrine cells stimulated by chyme; inhibits gastric motility, secretion of pancreatic enzymes, increased contraction of gall gladder: release of bile, stimulates enteropeptidase production required for activation of trypsinogen to trypsin
Trypsin
cleaves & activates:
- Protein digestion: Chymotrypsinogen, Proelastase, Procarboxypeptidase A & B
- Lipid digestion: Phospholipase A2 & Procolipase
Trypsin cleavage sites
+ve charged a.a.: Arginine & Lysine
Elastase cleavage sites
Serine, Alanine, Glycine (small a.a.)
Chymotrypsin cleavage sites
Bulky a.a.: Tryptophan, Tyrosine, Phenylalanine, Methionine, Leucine
Intestinal Protein Digestion
- Endopeptidases: Trypsin, chymotrypsin, elastase
- Exopeptidases: Carboxypeptidase A & B, aminopeptidases
Intestinal lipid digestion
- Pancreatic lipase & colipase: TAG (90% of dietary lipid)
- Cholesterylesterase: Cholesterol esters
- Phospholipase A1 & B: Phospholipds
Intestinal carb digestion
- Pancreatic amylase: alpha(1-4)
- Disaccharidases: secreted by brush border epithelium to break carbs to monosaccharides
Bile salts examples
Conjugated by either a molecule of Taurine or Glycine
- Glycocholic acid
- Glycochenodeoxycholic acid
- Taurocholic acid
- Taurochenodeoxycholic acid
