Hyperglycemia And Diabetes: Causes, Symptoms, And Mechanisms

Hyperglycemia And Diabetes: Causes, Symptoms, And Mechanisms

Name of the hypoglycaemic hormone of the body. Discuss its action, regulation of its secretion and features of deficiency of the hormone. (or) Insulin.
Answer:

Insulin:

• Insulin is the hypoglycaemic hormone.

Actions:

1. On carbohydrate metabolism.

• Increases the glucose entry into the tissues.
• Increases peripheral utilization of glucose.
• Promotes the rapid conversion of glucose into glycogen.
• Inhibits enzyme of glycogen breakdown.
• Decreases glucose output from the liver prevents gluconeogenesis.
• Prevents glycogenolysis.

2. On fat metabolism.

• Promotes the synthesis of free fatty acids and triglycerides.
• Facilitates transport of fatty acids into adipose tissue.
• Promotes storage of fat.

3. On protein metabolism.

• Facilitates transport of amino acids into cells from blood.
• Promotes amino-acid uptake and protein synthesis.
• Decreases protein breakdown.
• Prevents conversion of proteins into glucose.

4. On growth.

• Insulin promotes growth by protein anabolism.

Regulation:

1. Substrate control.

1. Control by carbohydrates.
   • Increase in blood glucose increases insulin secretion by its direct action on B-cells.
2. Control by protein and fat derivatives.
   • Mixture of amino acids and fat derivatives stimulates B-cells to increases the insulin secretion.

2. Hormonal control.

1. GIT hormones.
   • Gastrin, secretin, cholecystokinn and GIP increases insulin secretion.
2. Glucagon, growth hormone and corticosteroid stimulate insulin secretion indirectly.

3. Neural control.

1. By ANS.
   • Stimulation of parasympathetic nerves increases insulin secretion.
   • Stimulation of sympathetic nerves inhibits insulin secretion.
2. By CNS.
   • During feeding, vagal activity increases which increases insulin secretion.
   • During starvation, sympathetic activity increases which decreases insulin secretion.

4. cAMP.

• β-adrenergic receptor stimulation increases cAMP that increases insulin secretion.
• α-adrenergic receptor stimulation decreases cAMP that decreases insulin secretion.

Diabetes mellitus:

• It is a condition occurring due to deficiency of insulin hormone.

Features:

• Hyperglycemia – raised blood glucose.
• Glycosuria presence of glucose in urine.
• Polyuria – increased frequency of urine.
• Polydipsia – increased thirst.
• Polyphagia – intake of excess food.
• Dehydration.
• Loss of weight.
• Ketonuria.
• Osmotic diuresis.
• Acidosis due to excretion of ketoacids in urine.
• Acetone breathing – occur in severe ketoacidosis.
• Kussmaul breathing – due to severe acidosis.
• Circulatory shock- occur in severe diabetes.
• Coma- due to reduction in the concentration of bicarbonate ions.
• Increase in blood sugar level develops hyperosmolarity of plasma leading to coma.