Question

One of the constituents of the pancreatic juice which is poured into the duodenum in humans, is
A. Trypsinogen
B. Chymotrypsinogen
C. Trypsin
D. Both A and B

Answer 1

Hint: Digestion is the complex procedure by which the food is broken down into smaller molecules and converted chemically so that it can be easily absorbed by the cells and tissues of the body of an organism for growth, energy and repair. It involves various juices (enzymes) secreted in the mouth, stomach and the intestine by different glands.

Complete answer:
First let’s see about pancreas. Pancreas is an organ that is present behind the stomach. Pancreas being a dual gland it has dual function and secretes a number of enzymes into the bloodstream and into the pancreatic duct. There are a group of cells in the pancreas called the islets of Langerhans which perform the endocrine function. The exocrine part of the pancreas secretes pancreatic proteases, pancreatic lipase, pancreatic amylase, ribonuclease, deoxyribonuclease, gelatinase and elastase. The epithelial cells in pancreatic ducts are responsible for bicarbonate and water secretion into the pancreatic juice.
Trypsin is an enzyme which is released in its inactive form, trypsinogen. Trypsinogen is secreted by the pancreas (acinar cells) and secreted into the duodenum.
The next option is chymotrypsinogen. Chymotrypsinogen is also secreted by the pancreas and poured into the duodenum. Chymotrypsinogen is an inactive form and the active form is chymotrypsin.
So, from this information we can see that both trypsinogen and chymotrypsinogen is secreted from the pancreas.

Hence, the correct answer is option D – Both trypsinogen and chymotrypsinogen.

Note: Pancreas secretes three protease enzymes namely trypsinogen, chymotrypsinogen and procarboxypeptidase. All the three are activated in its inactive form. The activation of trypsinogen to trypsin is done by the enzyme enterokinase. Trypsin in turn activates the chymotrypsinogen to chymotrypsin. Trypsin also activates procarboxypeptidase to carboxypeptidase.