Question

Cholecystokinin is secretion of
A) Stomach which stimulates pancreas to release pancreatic juice.
B) Liver synthesized from cholesterol and controls secondary sex characters.
C) Duodenum and makes the gallbladder contract and release bile
D) Goblet cells of ileum and stimulates secretion of succus entericus.

Answer 1

Hint:Cholecystokinin is a peptide hormone which is secreted in the small intestine. It helps in the digestion of fats and proteins.

Complete answer:
Cholecystokinin is secreted by the I cells present in the lining of the upper part of the stomach called Duodenum. Introduction of acids like fatty acids, hydrochloric acid and amino acids into the Duodenum stimulates the secretion of Cholecystokinin. It is secreted with secretin. The cells responsible for synthesis and secretion of the hormone Cholecystokinin are enteric cells of the Duodenum. Presence of chyme in the small intestine stimulates its secretion in the blood. It interacts with the receptors on pancreatic acinar cells and thus in turn orders the secretion of digestive enzymes. The main function of this hormone is to reduce the appetite.

Let us analyse the options to find the correct answer
Option A, B and D: Cholecystokinin is not a secretion of stomach, liver or ileum. Hence, these are incorrect options.
Option C: Cholecystokinin is secreted by Duodenum and it also stimulates the gallbladder to contract and release the stored bile in the small intestine. Hence, this is the correct option.

Thus, the correct answer is Option (C ) Duodenum and makes the gallbladder contract and release bile.

Note:Functions of Cholecystokinin
i) It mediates digestion by stimulating the pancreatic cells to release pancreatic juices. These enzymes catalyse the digestion of partially digested fats and proteins.
ii) It also causes the contraction of gallbladder which stimulates the secretion of Bile into the intestine. Bile helps in emulsification of fats.
iii) CCK also suppresses hunger by acting on the receptors in the central nervous system. Thus, it acts as a satiety hormone.
iv) It is also known to increase anxiety.