Question

Give the full form of ADH. Name the gland that secretes it. Under what condition of the body is it released? What is its role in forming hypertonic urine? What is the disease caused due to the failure of its secretion?

Answer 1

Hint: It is secreted by a gland present near the cerebral hemispheres and also known as vasopressin. When secreted in high concentrations, it raises the blood pressure by inducing moderate vasoconstriction.

Complete answer:
The full form of ADH is antidiuretic hormone and is synthesized in the hypothalamus and released by the posterior pituitary or neurohypophysis. This hormone is also called vasopressin or argipressin.
It is a peptide hormone which after synthesis in the hypothalamus, travels to the posterior pituitary via the axon of the neural cells. It is released in a condition when there is hypertonicity in the extracellular fluid i.e. the osmotic pressure of the extracellular fluid becomes higher than the normal due to a decrease in water content.
After secretion, it increases the water reabsorption through the kidney tubules to restore the normal osmolarity of extracellular fluid and due to this water reabsorption, the water content in urine decreases and thus it causes the formation of hypertonic urine.
If the secretion of vasopressin fails, it leads to a condition called diabetes insipidus in which there is increased blood sodium concentration and excess urine production i.e. polyuria.

Note: As this hormone has an effect on the osmolarity of extracellular fluid by water reabsorption, the deficiency causes less absorption of water from the kidney tubules and thus it is obvious that the solute concentration in the extracellular fluid will increase and the condition leads to disease.