Which of the following body systems breaks down proteins into amino acids?
A.
Digestive
B.
Excretory
C.
Circulatory
D.
Endocrine
The Correct Answer and Explanation is:
The correct answer is A. Digestive.
Explanation:
The digestive system is responsible for breaking down food into smaller molecules that the body can absorb and use for energy, growth, and repair. Proteins, one of the major macronutrients, are broken down into their building blocks, amino acids, through the process of digestion.
The process of protein digestion begins in the stomach, where the enzyme pepsin plays a crucial role. The stomach secretes hydrochloric acid (HCl), which helps denature the proteins, unraveling their complex structures. This makes the proteins more accessible to enzymes like pepsin, which starts breaking down the long chains of amino acids into smaller peptide fragments.
The partially digested proteins then move into the small intestine, where further digestion occurs. In the small intestine, enzymes called proteases (such as trypsin and chymotrypsin, secreted by the pancreas) break down these peptide fragments into even smaller chains. Another enzyme, peptidase, breaks down these small peptides into individual amino acids. The amino acids are then absorbed by the cells lining the small intestine and transported into the bloodstream.
Once in the bloodstream, amino acids are delivered to cells throughout the body, where they are used for various purposes, such as synthesizing new proteins needed for growth, tissue repair, and enzymatic functions. Amino acids can also be used in the synthesis of hormones and neurotransmitters or be converted into energy when necessary.
In contrast, the excretory system removes waste products from the body, the circulatory system transports nutrients and oxygen, and the endocrine system regulates hormones. None of these systems are directly involved in the breakdown of proteins into amino acids, making the digestive system the correct answer.