Digestion 2 Flashcards
By what enzyme are proteins hydrolysed?
Pepsidases
What are the 2 different types of pepsidase?
Endopepsidase and Exopepsidase
What is the function of endopepsidase?
They cleave internal peptide bonds and breakdown large polypeptides into smaller oligopeptides
What is the function of exopepsidase?
They cleave from the ends of the protein/peptide and breakdown these oligopeptides into di- and tri- peptides and amino acids
What are the 3 products of protein digestion?
Tri-peptides
Di-peptides
Amino Acids
What does the low pH of stomach acid do for protein digestion?
Denatures the protein and causes unravelling of the peptide chain to make the protein more accessible to digestive enzymes
What do chief cells in the gastric mucosa secrete?
Pepsinogen
What is pepsinogen?
The inactive precursor of pepsin
What initially activates pepsinogen?
Low pH of stomach acid
What are the functions of pepsin?
- Autocatalyses further conversion of pepsinogen to pepsin
- Digests target protein into large peptide fragments and amino acids
- This then stimulates CCK hormone release in duodenum
What are the 2 hormones issued in the duodenum that are secreted?
Secretin and CCK
What stimulates the release of SECRETIN and what is its action?
Stimulated by: acidity of stomach acid into duodenum
Action: stimulates secretion of bicarbonate rich pancreatic fluid to neutralise acid
What stimulates the release of CCK and what is its action?
Stimulated by: breakdown of protein into large peptide chain and amino acids by pepsin
Action: causes contraction of gall bladder and relaxation of sphincter of Oddi and so promotes entry of bile and pancreatic juices into duodenum
What are zymogens?
pancreatic enzymes that are released as inactive precursors
What do duodenal enteropeptidases do?
Convert trypsinogen to trypsin