Dietary and endogenous proteins are hydrolyzed into their constituent amino acids and a few small peptide fragments by gastric pepsin and the pancreatic proteolytic enzymes.
Many small peptides are converted into their respective amino acids by the aminopeptidases located in the brush borders of the small-intestine epithelial cells.
Amino acids are absorbed into the epithelial cells by means of Na and energy-dependent secondary active transport via a symporter. Various amino acids are transported by carriers specific for them.
Some small peptides are absorbed by a different type of symporter driven by h ,Na ,and energy-dependent tertiary active transport.
G
Most absorbed small peptides are broken down into their amino acids by intracellular peptidases.
Amino acids exit the cell at the basal membrane via various passive carriers.
Amino acids enter the blood by simple diffusion. (A small percentage of di-and tripe prides also enter the blood intractable)