ABSTRACT
The conscious sensation of thirst, the feeling of a need to drink water, only occurs if the body reaches a state of deficit. If water is lost from the intracellular fluid, the cell goes outside the optimal conditions for cellular processes. The intracellular fluid is separated from the interstitial fluid by complex cell membranes, semipermeable membranes, which contain receptors for various chemical substances. The amount of water in the body needs to be controlled for two main reasons. First, cellular processes depend on chemical reactions between substances in solution within the cells. Clearly, the control of water in the body must be closely connected with the control of electrolytes, and particularly of sodium. The second reason to control the water content of the body is to maintain the total volume of water. This allows blood pressure to be maintained, which is essential for proper circulation of blood to all tissues.
