MECHANISM OF THIRST OR THIRST MOTIVATION
Hormonal Mechanism
Anti-di-uretic hormone (ADH) is the hormone that regulates the loss of water through the kidneys. However, this physiological mechanism is not directly involved in thirst motivation.
Double Depletion Hypothesis of Thirst
Thirst motivation and drinking are mainly triggered by two conditions of the body:
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- Loss of water from the cells
- Reduction of blood volume
- When water is lost from bodily fluids, water leaves the interior of the cells, thus leading to the dehydration of the cells.
- Nerve cells called osmoreceptors, situated in the anterior hypothalamus generate a nerve impulse when dehydrated.
- These nerve impulses act as a signal for thirst and drinking.
- Thirst triggered by the loss of water from the osmoreceptors is called cellular-dehydration thirst.
- Loss of water from the body also leads to hypovolemia (decrease in the volume of blood).
- When the volume of blood reduces, the blood pressure also goes down.
- This drop in blood pressure stimulates the kidneys to release an enzyme called renin.
- After several intermediate steps, renin leads to the production of angiotensin II, that circulates in the blood and leads to drinking behavior.
- The idea that cellular dehydration and hypovolemia contribute to thirst and drinking behavior is called the double depletion hypothesis.
Nerve cells called osmoreceptors, situated in the anterior hypothalamus generate a nerve impulse when dehydrated.
These nerve impulses act as a signal for thirst and drinking.
Thirst triggered by the loss of water from the osmoreceptors is called cellular-dehydration thirst.
Loss of water from the body also leads to hypovolemia (decrease in the volume of blood).
When the volume of blood reduces, the blood pressure also goes down.
This drop in blood pressure stimulates the kidneys to release an enzyme called renin.
After several intermediate steps, renin leads to the production of angiotensin II, that circulates in the blood and leads to drinking behavior.
The idea that cellular dehydration and hypovolemia contribute to thirst and drinking behavior is called the double depletion hypothesis.