Gastric Physiology and Digestive Enzymes - Intermediate - Class X

Rennin (chymosin) is an enzyme that helps in the digestion of milk proteins. It is found in the gastric juice of young mammals (like calves) and human infants to digest milk, but its production decreases significantly in human adults.

Rennin is an enzyme primarily found in the gastric juice of infant mammals to coagulate milk. In adult humans, rennin is typically absent or present in negligible amounts.

Rennin is the specific gastric enzyme in infant mammals that converts soluble caseinogen into insoluble casein, which is then digested by pepsin.

Zymogen cells, also known as chief cells or peptic cells, are located in the gastric glands and are responsible for secreting pepsinogen, the inactive precursor to pepsin.

Pepsin is a protease that requires a low pH environment, provided by hydrochloric acid in the stomach, to become active and function optimally.

Gastric acid secretion is stimulated by multiple pathways: gastrin (hormonal), histamine (paracrine), and vagal activation (neural). Therefore, all these factors contribute to the process.

Chief cells (or zymogen cells) are the primary source of pepsinogen secretion in the gastric glands of the stomach.

Liquids, especially those like beer or water, pass through the stomach much faster than solid foods like proteins, carbohydrates, or fats, which require significant mechanical and chemical breakdown.

Pepsin is produced as the inactive zymogen pepsinogen by the zymogen (chief) cells of the stomach lining.

Pepsinogen is an inactive proenzyme. It is converted into the active enzyme pepsin by the acidic environment created by hydrochloric acid (HCl) in the stomach.

Rennin is the enzyme responsible for the coagulation of milk protein, specifically acting on caseinogen to form casein.

Pepsin is a digestive protease that is secreted and functions specifically within the stomach.

The gastric juice in the stomach is highly acidic due to the secretion of hydrochloric acid, typically maintaining a pH range between 1.5 and 3.0.

Pepsin is the enzyme secreted by the stomach wall that acts on proteins, such as casein, to begin the digestive process.

Gastric juice contains hydrochloric acid, giving it a very low pH (highly acidic) compared to saliva, bile, or pancreatic juice, which are neutral or alkaline.

HCl activates the zymogen pepsinogen into pepsin. Similarly, enterokinase (an intestinal enzyme) activates the pancreatic zymogen trypsinogen into trypsin.

Ptyalin (salivary amylase) functions in a neutral pH and is inactivated by the acidic environment of the stomach, whereas pepsin requires this acidic environment to be activated.

Pepsin is the primary gastric enzyme that hydrolyzes proteins into smaller peptide fragments.

Gastrin is a hormone secreted by G-cells in the stomach that stimulates the parietal cells to secrete gastric acid and promotes gastric juice secretion.

Pepsin is the primary enzyme responsible for the digestion of proteins in the stomach.

Zymogenic (chief) cells in the stomach are responsible for the secretion of pepsinogen, the inactive precursor of pepsin.

Prorennin (the precursor to rennin) is produced by the zymogen (chief) cells of the gastric glands in the stomach.

Peptic cells, also known as chief cells or zymogen cells, are responsible for secreting pepsinogen into the stomach lumen.

Rennin is a proteolytic enzyme specifically found in the gastric juice of young mammals, which is essential for the coagulation of milk protein (casein). Other enzymes like amylase or invertase are involved in carbohydrate digestion.

Parietal cells (also known as oxyntic cells) in the gastric glands secrete hydrochloric acid and intrinsic factor. Intrinsic factor is a glycoprotein necessary for the absorption of vitamin B12 in the small intestine.

Rennin is the specific enzyme in the gastric juice of infants that converts soluble milk protein (casein) into insoluble paracasein, facilitating its digestion. Pepsin is a general proteolytic enzyme, while lactase digests lactose sugar.

Pepsin is a gastric enzyme that functions optimally in a highly acidic environment. Its peak activity occurs at a pH range of approximately 1.6 to 2.4, which corresponds to the acidic conditions created by hydrochloric acid in the stomach.

Reaction (i) is correct as HCl activates pepsinogen to pepsin. Reaction (v) is correct as trypsin breaks down peptones into dipeptides. Reaction (ii) is incorrect because pepsinogen is not the enzyme acting on proteins; pepsin is. Reaction (iii) is incorrect because enterokinase, not HCl, activates trypsinogen. Reaction (iv) is correct, but the option set identifies (i) and (v) as the intended answer.

Pepsin is a gastric protease that requires an acidic environment to function. Its optimal pH is approximately 2.0, matching the acidic conditions of the stomach lumen.

Starch digestion begins in the mouth via salivary amylase. Proteins begin digestion in the stomach. Fats and cellulose are not significantly digested in the mouth or esophagus; therefore, they reach the stomach in a largely undigested state.

(i) Salivary amylase hydrolases proteins to amino acids - False

The enzyme that initiates protein digestion is 'pepsin'.

In the digestion of milk, the enzyme rennin converts casein into paracasein. This paracasein then reacts with calcium ions (Ca++) to form insoluble calcium paracaseinate, which is the curdling process.