Question

Glycogen is converted into glucose by
a) Insulin
b) Glucagon
c) Both insulin and glucagon
d) Galactase

Answer 1

Hint: The alpha cells present in the pancreatic islets secrete a peptide hormone which helps in maintaining the concentration of sugar and fatty acids in the bloodstream. It raises blood sugar concentration by breaking down the reserve food material in the liver.

Complete answer:
The process by which glycogen is converted into sugar is known as glycogenolysis and in this process, the primary carbohydrate that is stored as reserve food material in liver and muscles is broken down into glucose and not it only restores the required amount of sugar in the blood but also provides immediate energy. The hormone glucagon helps in this conversion by strongly opposing the actions of insulin. The secretion of this hormone is stimulated by a condition of low blood glucose concentration and also during exercise. Besides promoting glycogenolysis, it also stimulates gluconeogenesis i.e. the production of glucose from amino acids.

Additional information:
a) Glucagon is a pancreatic hormone that is secreted by the alpha cells present in pancreatic islets. It is a peptide hormone containing 29 amino acids and has a high degree of similarity with several glucagons like peptides that are secreted by the cells present in the gastrointestinal tract.
b) During fasting, the concentration of sugar in our blood decreases, and in that situation, the hormone glucagon maintains the optimum sugar concentration by the process of glycogenolysis to keep us alive.
So, the correct answer is ‘Glucagon’.

Note: There are three types of cells present in the Islets of Langerhans of the pancreas and all these cells are involved in secreting different important hormones. They are –
a) Alpha cells – these cells secrete the hormone glucagon which converts glycogen to glucose and increases blood sugar concentration.
b) Beta cells – these cells produce the hormone insulin which is an antagonist to the glucagon and converts glucose to glycogen which is stored in the liver.
c) Delta cells – these cells secrete the hormone somatostatin which is also produced by several other endocrine cells in the body and inhibits the secretion of other hormones, the activity of the gastrointestinal tract, and the rapid reproduction of normal and tumor cells.

Fig.- Pancreatic tissues