Evolutionarily, human organisms developed well-controlled regulatory mechanisms that maintain fluid balance because water is an essential medium for all biochemical reactions in the body. Indeed, specific hormones and signaling molecules, like aldosterone, cortisol, and antidiuretic hormone, are known to regulate water-salt balance in the body by promoting or stopping diuresis and thirst (Rakova et al., 2017). External factors, like salt and sugar intake, can result in fluid retention or excretion, respectively. Furthermore, some pathologies may alter water release, causing edema or dehydration. Endocrine and neural systems maintain the equilibrium between the amount of fluid intake and output, keeping the stability of minerals inside cells and tissues.
The human body loses fluid in sweat and urine, but the balance is controlled by proper water intake, caused by thirst mechanisms. The two primary systems that regulate fluid homeostasis are thirst, initiated or suppressed by neural circuits, and adrenal and hypothalamic hormones that affect kidney function (Gizowski & Bourque, 2018; Rakova et al., 2017). Firstly, thirst is elicited under such circumstances as hypovolemia, hyperosmolarity of plasma, feeding, hyperthermia, and after sleep due to changes in the electrolyte balance in the extracellular space (Gizowski & Bourque, 2018). Coordination occurs in various nuclei in the neocortex, thalamus, and brainstem (Gizowski & Bourque, 2018). Secondly, increased mineral elements in the circulation lead to fluid retention due to elevated aldosterone release from the adrenal glands. Its effect on nephrons is that they start to absorb more water in their tubular network (Rakova et al., 2017). Moreover, aldosterone and cortisol are produced rhythmically under normal conditions, balancing fluid accrual or excretion (Rakova et al., 2017). Overall, the interconnectedness of these two systems plays an essential role in water balance in the organism.
In summary, fluid homeostasis in the human body is attained through tightly controlled endocrine and neural mechanisms. Neural circuits enhance or diminish thirst and subsequent water intake, while adrenal and hypothalamic hormones directly affect kidneys, causing increased or decreased fluid reabsorption. It means that if a person increases one’s salt intake, it may cause tissue edema; however, if mineral and water consumption is moderate, the regulation will be continued rhythmically.
References
Gizowski, C., & Bourque, C. W. (2018). The neural basis of homeostatic and anticipatory thirst. Nature Reviews Nephrology, 14(1), 11-25. Web.
Rakova, N., Kitada, K., Lerchl, K., Dahlmann, A., Birukov, A., Daub, S., Kopp, C., Pedchenko, T., Zhang, Y., Beck, L., Johanes, B., Marton, A., Müller, D.N., Rauh, M., Luft, F.C., & Titze, J. (2017). Increased salt consumption induces body water conservation and decreases fluid intake. The Journal of Clinical Investigation, 127(5), 1932-1943. Web.