This set of Molecular Endocrinology Multiple Choice Questions & Answers (MCQs) focuses on “Glucagon Hyperglycaemic Glycogenolytic Factor (HGF)”.
1. Which cells produces glucagon hormone that regulates glucose metabolism?
a) Alpha cells of islets of Langerhans
b) Beta cells of islets of Langerhans
c) Acinar cells
d) Parafollicular cells
View Answer
Explanation: Glucagon is a hormone formed by the alpha-cells of the pancreatic islets of Langerhans. It is an important hormone involved in the rapid mobilization of hepatic glycogen by glycogenolysis to deliver glucose and to a smaller extent, adipose tissue FA.
2. What is the role of carboxypeptidase B and trypsin-like peptidases in glucagon formation?
a) Inactivates glucagon
b) Hydrolyze proglucagon into glucagon
c) Helps in the breakdown of glucagon
d) Dehydrates glucagon
View Answer
Explanation: In alpha-cells, glucagon is first synthesized as a pro-hormone, “proglucagon”. In alpha-cells, lysosomal enzyme peptidases such as carboxypeptidase B and trypsin-like peptidases hydrolyze pro-glucagon to generate glucagon and inactive peptides from both its N-terminal end and C-terminal end.
3. Where is the glucagon-like immuno-reactive factor (GLI) found in the human body?
a) Colon
b) Jejunum
c) Gastric and duodenal mucosa
d) Epithelial lining of endoplasmic reticulum
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Explanation: Gastric and duodenal mucosa have been known to have a glucagon-like immuno-reactive factor (GLI). Though not equivalent to the pancreatic hormone, GLI is immunologically related. The secretion of glucagon is triggered by protein intake, low blood glucose concentrations (hypoglycemia), and exercise.
4. Unlike insulin, glucagon does not require Zinc for its activity.
a) True
b) False
View Answer
Explanation: Glucagon, unlike insulin, does not need zinc or other metals for its crystallization. Glucagon does not contain cystine, proline or isoleucine, but it contains tyrosine, tryptophan, and methionine. Zinc, however, is considered to play a major role in stabilizing insulin hexamers and in storing insulin in the pancreas because it can boost insulin binding to hepatocyte membranes.
5. Glucagon decreases glycogenolysis in liver.
a) True
b) False
View Answer
Explanation: Glucagon in the liver improves glycogenolysis. It does not induce glycogenolysis in muscles as the glucagon specific receptors are absent from the muscle cell membrane. Glucagon facilitates the liver conversion of glycogen into glucose (glycogenolysis), induces the synthesis of de novo glucose (gluconeogenesis) and prevents the breakdown of glucose (glycolysis) and the formation of glycogen (glycogenesis).
6. Which hormones help in the lipolytic action of glucagon?
a) Calcitonin
b) Thyroid hormones
c) Sex hormones
d) Insulin
View Answer
Explanation: Thyroid hormones assist in glucagon’s lipolytic action. The number of glucagon specific receptors on adipocytes is increased by these hormones. Hypothyroidism is associated with reduced insulin sensitivity, and it has been shown that glucose tolerance and hypothyroidism treatment have enhanced these effects.
7. What is the role of glucagon in protein metabolism?
a) Reduces protein metabolism
b) Enhances protein metabolism
c) Blocks protein metabolism
d) Only promotes catabolism
View Answer
Explanation: By reducing the integration of amino acids into peptide chains, Glucagon inhibits protein synthesis. This is due to the inactivation by protein kinase whose function is stimulated by the increase in c-AMP. This activity is performed by glucagon hormone.
8. Why is glucagon used in the treatment of heart diseases?
a) Increase in oxygen consumption
b) Decrease the force of contraction
c) Exerts a negative ionotropic effect on heart
d) Exerts a positive ionotropic effect on heart
View Answer
Explanation: Without causing myocardial irritability, Glucagon exerts a +ve ionotropic impact on the heart. Glucagon is therefore used in the treatment of cardiac failure, especially in the treatment of heart failure and cardiogenic shock.
9. What is the reason behind the calorigenic action of glucagon?
a) Increased hepatic deamination of amino acids
b) Hyperglycemia Perse
c) Decreased hepatic deamination of amino acids
d) Hypoglycemia Perse
View Answer
Explanation: Glucagon increases the heat and BMR. The calorigenic action is not due to Perse hyperglycemia but is likely due to increased amino acid hepatic deamination, with thyroid hormones promoting the use of deaminated residues.
10. Which among the following is a disease that can be treated with glucagon hormone?
a) Kidney failure
b) Acute Pancreatitis
c) Gout
d) Phenylketonuria
View Answer
Explanation: Recently, glucagon has also been used in the management of acute pancreatitis because of its inhibitory effect on pancreatic exocrine secretions. However, the most important use is in the treatment of insulin-induced hypoglycemia.
Sanfoundry Global Education & Learning Series – Molecular Endocrinology.
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