Where does protein digestion begin in the human digestive system?

Where does protein digestion begin in the human digestive system?

• A. Stomach
• B. Esophagus
• C. Mouth
• D. Small Intestine

Answer: (A)

Protein digestion starts in the stomach. The acidic environment from hydrochloric acid denatures proteins and activates pepsin from its precursor pepsinogen. Pepsin begins cleaving peptide bonds, starting the breakdown of proteins into smaller peptides. In the mouth, chewing and saliva mainly handle carbohydrates, with little to no significant protein digestion. The esophagus simply transports food and doesn’t digest proteins. In the small intestine, further digestion by pancreatic enzymes continues, but the initial digestion of proteins occurs in the stomach.

Protein digestion starts in the stomach. The acidic environment from hydrochloric acid denatures proteins and activates pepsin from its precursor pepsinogen. Pepsin begins cleaving peptide bonds, starting the breakdown of proteins into smaller peptides. In the mouth, chewing and saliva mainly handle carbohydrates, with little to no significant protein digestion. The esophagus simply transports food and doesn’t digest proteins. In the small intestine, further digestion by pancreatic enzymes continues, but the initial digestion of proteins occurs in the stomach.