Protein digestion

Question 1

proteolytic enzyme secretion

Answer 1

secreted as proenzymes from the pancreas; Trypsinogen is activated by enterokinase into trypsin. Trypsin activates other pancreatic proteolytic enzymes

Question 2

luminal phase of protein digestion

Answer 2

exogenous dietary protein, enters the lumen of the digestive system, HCL and pepsin from the stomach, Hcl denatures proteins; from the pancreas proteolytic enzymes break proteins into amino acids and small peptides.

Question 3

membranous phase (glycocalyx) of protein digestion

Answer 3

aminopeptidases; enzymes produced by enterocytes, break down the small peptides further.

Question 4

cystosolic phase (enterocyte cytosol)

Answer 4

intracellular peptidases break down remaining small peptides into amino acids.

Question 5

Amino acid absorption across basolateral membrane into enterocytes

Answer 5

Secondary active Na+ dependant amino acid co-transporters;Na+ and amino acid travel through co-transporter channels together.

Question 6

small peptide absorption actoss basolateral membrane into enterocytes

Answer 6

Tertiary active H+ dependant co-transporter ( PepT1) travel by facilitated diffusion

Question 7

absorption of intact proteins into enterocytes

Answer 7

by endocytosis