Majority of amino acids absorbed by the small intestine are absorbed as peptides
options:
True
False
The correct answer and explanation is:
The correct answer is True.
The majority of amino acids absorbed by the small intestine are absorbed as peptides. When proteins are ingested, they are broken down by digestive enzymes such as pepsin in the stomach and trypsin and chymotrypsin in the small intestine. These enzymes break proteins into smaller peptides and amino acids.
Most absorption of amino acids occurs in the small intestine, specifically in the duodenum and jejunum. However, rather than being absorbed directly as free amino acids, a significant portion is absorbed as dipeptides and tripeptides. This happens because the transporters on the cells lining the intestine (enterocytes) are more efficient at taking up these small peptides than individual amino acids. Once inside the enterocyte, these peptides are further broken down into amino acids by intracellular peptidases.
After this breakdown, the free amino acids can then enter the bloodstream through specific transporters. This mechanism is more energy-efficient and allows for the absorption of amino acids in a quicker and more concentrated form. In addition, the absorption of peptides instead of individual amino acids helps reduce the potential energy cost of transporting amino acids across the cell membranes.
This absorption process is essential for overall protein metabolism and nutrient availability in the body. The ability of the intestine to absorb peptides and then break them down helps maintain an efficient system for protein digestion and absorption, ensuring that the body has the necessary building blocks to synthesize new proteins for various physiological functions.