Where is protein broken down in the digestive system?

Protein breakdown in the digestive system primarily occurs in the stomach and small intestine. Here's a step-by-step explanation of where protein is broken down:

1. Stomach:

- Gastric juices, primarily containing hydrochloric acid and the enzyme pepsin, play a crucial role in protein digestion in the stomach.

- Pepsin is activated by the acidic environment and breaks down proteins into smaller polypeptides.

- The muscular churning of the stomach further helps mix the proteins with digestive juices, facilitating the breakdown process.

2. Small Intestine:

- Once the partially digested proteins leave the stomach, they enter the small intestine.

- The pancreas secretes pancreatic enzymes, including trypsin, chymotrypsin, and carboxypeptidase, into the small intestine. These enzymes further break down the polypeptides into smaller amino acids.

- The brush border of the small intestine, which lines the intestinal walls, contains additional enzymes, such as dipeptidases and aminopeptidases. These enzymes break down dipeptides and tripeptides into individual amino acids.

Throughout this process, the liver produces bile, which helps in the digestion and absorption of fats. Bile emulsifies dietary fats, making them easier for enzymes to break down and digest.

Finally, the products of protein digestion, mainly amino acids, are absorbed through the intestinal wall and transported to various tissues and organs for utilization and synthesis of new proteins.