Lecture 14 - Protein Digestion

Question 1

Protein Quality characteristics?

Answer 1

Digestibility (animal vs plant) and whether a source is complete w the essential amino acids

Question 2

Protein digestion: Mouth?

Answer 2

Chewing and crushing moisten protein rich foods mixed w saliva

Question 3

Protein Digestion: Stomach?

Answer 3

Pepsin and HCl break down protein into smaller polypeptides and A.A.

Question 4

Pancreatic secretions?

Answer 4

Endopeptidases which is converted into Trypsin, Chemotrypsin and Elastase

Question 5

Pancreatic enzymes catalyse?

Answer 5

Polypeptides -> Tripeptides, Dipeptides, Amino Acids

Question 6

Peptides -> Amino Acids enzymes?

Answer 6

Tripeptidases, dipeptideases, aminopeptidases

Question 7

Pancreatic enzyme cascade?

Answer 7

Membrane-bound enteropeptidases activate trypsinogen, presence of trypsinogen triggers -ve feedback loop as well as activationg other inactive proteases, and so on

Question 8

Chemical types of absorption at small intestine?

Answer 8

Sodium pump into enterocyte, passive diffusion into blood stream

Question 9

How to measure protein levels?

Answer 9

Measure amount of body nitrogen products excreted e.g. urea

Question 10

Nitrogen balance?

Answer 10

Though total body protein is being recycled using amino acid products of protein breakdown through enterocyte regenration, protein intake should match that excreted in faeces and urine

Question 11

Factors causing negative nitrogen balance?

Answer 11

Decreased protein intake, starvation, injury, illness/burns/infections, post-operative conditions, cancers, lactation

Question 12

Factors causing positive nitrogen balance?

Answer 12

Increased intake, growth, pregnancy, recovery from illness