In this article we will discuss about:- 1. Actions of Glucagon 2. Regulation of Secretion of Glucagon 3. Features.
Glucagon is a peptide hormone. It is secreted by alpha or A cells of islets of Langerhans. Unlike insulin which is a hypoglycemic agent, glucagon is a hyperglycemic agent.
Actions of Glucagon:
1. Carbohydrate metabolism
2. Fat metabolism
On Carbohydrate Metabolism:
i. It is a hyperglycemic agent and hence increases blood glucose level.
ii. Brings about glycogenolysis in liver only. Glucose produced by glycogenolyis is added on to circulation.
iii. Increases gluconeogensis in liver.
On Fat Metabolism:
i. It is a lipolytic agent.
ii. Acts on adipose tissue and increases the activity of hormone sensitive lipase.
iii. This brings about increase lipolysis. Free fatty acids are added on to circulation due to breakdown of neutral fats and triglycerides.
iv. Utilization of fatty acids to supply energy may lead to ketone body formation.
Regulation of Secretion of Glucagon:
The concentration of blood glucose affects the secretion of hormone. Decrease in the blood glucose level will increase the secretion of glucagon and vice versa when level of glucose is increased in circulation.
Apart from this, some of the other factors which can affect the secretion of glucagon are:
Stimulators:
i. Ingestion of proteins.
ii. Sympathetic stimulation
One of the important factors which decrease the secretion of glucagon is somatostatin.
Features of Excess of Glucagon:
i. Glucose level increased and keto acids in circulation.
ii. Gluconeogenesis markedly increased.
iii. Generalized reduction in AA level and decreased excretion of nitrogen.
iv. Loss of weight.