Did you know...
The fluid intake is stimulated inside the body by two different physiological mechanisms:
These two stimula cause the thirst sensation through different mechanisms.
The thirst which is stimulated by hypovolemia is called volumetric thirst; the vasopressin, also called anti-diuretic hormone (ADH), regulates the correct volume and the saline concentration in blood; if you are out of water, the blood volume diminishes and the salt concentration in the blood increases.
The other thirst stimulus, blood hypertonicity is perceived thanks to the vascular organ of the lamina terminalis (OLVT). When the blood becomes hypertonic, water leaves the cells through the osmosis process and thanks to OVLT the body has motivation to drink water in condition of dehydration.*
During summer months, when temperature increases considerably, it is recommended to drink a lot of water to rehydrate and recover the lost fluids with the sweating.
*da: "Neuroscience. Exploring the brain".