Question

How is thirst detected and what are the responses to thirst? Include descriptions of nervous and endocrine system involvement.

Answer 1

Thirst center is in the lateral nucleus of hypothalamus. There are some osmoreceptors in the areas adjacent to thirst center. When the ECF volume decreases, the osmolality of ECF is increased. If the osmolarity increases by 1% to 2%, the osmoreceptors are stimulated. Osmo- receptors in turn, activate the thirst center and thirst sensation is initiated. Now, the person feels thirsty and drinks water. Water intake increases the ECF volume and decreases the osmolality.   
Renin increases water intake by stimulating the thirst center.