Describe the process of digestion in digestive system.

Explanation

Protein digestion begins in the stomach. The food entered into the stomach is mixed thoroughly with the gastric juice of the stomach by the churning movements of its muscular wall and the product is called chyme. The main components of gastric juice are protein digestive enzymes, hydrochloric acid and mucus.
HCI provides the acidic pH (1.8) which is optimal for the action of pepsin. The proenzymes of gastric juice, the pepsinogen and. prorennin on exposure to hydrochloric acid are converted into the active enzymes, pepsin and rennin respectively. Pepsin converts proteins into proteoses and peptones. Rennin is a proteolytic enzyme found in the gastric juice of infants. It acts on the milk protein, the casein in the presence of calcium ions and converts it into calcium paracaseinate and proteoses. Pepsin acts on calcium paracaseinate and converts it into peptones. The entire process of protein digestion in the stomach takes about 4 hours.
Propennin (inactive) `overset(HCl)to ` Rennin (active)
Pepsinogen (inactive( overst(HCl) to ` Pepsin (active)
Casein `underset(Ca ^(+2)) overset("Rennin") to ` Calcium paracaseinate
Calciumparacaseinate overset("Pepsin")to ` Petones
Proteins `overset("Pepsin") to `Proteoses + Peptones