Protein digestion is the process of breaking down complex protein molecules into smaller peptides and, ultimately, individual amino acids, which the body can then absorb and use.
Here's a breakdown of the protein digestion process:
1. Stomach:
- Gastric Juice: The stomach secretes gastric juice containing hydrochloric acid (HCl) and pepsinogen.
- HCl Activation: HCl converts inactive pepsinogen into its active form, pepsin.
- Pepsin's Role: Pepsin is an enzyme that begins the breakdown of proteins (proteolysis) by cleaving the peptide bonds, breaking the long protein chains into smaller peptides.
- Churning Action: The stomach's muscular contractions further aid in breaking down food and mixing it with gastric juices.
2. Small Intestine:
- Pancreatic Enzymes: Partially digested proteins (peptides) move into the small intestine, where enzymes secreted by the pancreas further break them down. Key pancreatic enzymes include:
- Trypsin: Breaks down proteins into smaller peptides.
- Chymotrypsin: Similar to trypsin, breaks down proteins into smaller peptides.
- Carboxypeptidase: Breaks down peptides by removing amino acids from the carboxyl (COOH) end of the peptide chain.
- Intestinal Enzymes: The small intestine's lining also secretes enzymes, such as peptidases, that break down the remaining small peptides into individual amino acids.
3. Absorption:
- Amino Acid Uptake: The individual amino acids are then absorbed through the intestinal lining and enter the bloodstream.
- Transportation: The bloodstream transports the amino acids to various parts of the body where they are used for protein synthesis, enzyme production, hormone creation, and other essential functions.
Summary Table:
| Organ | Secretions/Enzymes | Action |
|---|---|---|
| Stomach | HCl, Pepsinogen | HCl activates pepsin; pepsin begins protein breakdown into peptides. |
| Small Intestine | Trypsin, Chymotrypsin, Carboxypeptidase, Peptidases | Further breakdown of peptides into amino acids. |
In essence, protein digestion involves enzymatic hydrolysis in the stomach and small intestine, resulting in the breakdown of proteins into absorbable amino acids.
