Question

Discuss the major aspects of water regulation in the body.

Answer 1

Water regulation in body is essential to maintain homeostasis.It includes regulation of intake and regulation of output.

1.Regulation of intake

Fluid enters the body as preformed water,ingested food and drink,a minimal amount through metabolic process.

Thirst is the sensation regulated by hypothalamus

Osmoreceptors senses the increase in plasma osmolality,which stimulate hypothalamus to produce the sensation of thirst. Osmoreceptors also stimulate ADH secretion through hypothalamic stimulation .ADH increase reabsorption of water from renal tubules thus maintaining water balance.

Another method is through renin angiotensin system.Here the macula densa(osmoreceptors in the loop of Henle) stimulate juxta glomerular apparatus to produce Renin which stimulate conversion of angiotensinogen into Angiotensin I.Angiotensin I converts to angiotensin II in the presence of angiotensin converting enzyme it stimulate hypothalamus,it initiate sensation of thirst, vasoconstriction, aldosterone release and thus results in increased water reabsorption.

Regulation of Output

Water output is mainly through urination,excretions and perspiration

Fluid deficiency increases ADH and aldosterone release which causes water retention and thus decrease urine output.

When fluid volume excess, decrease secretion of ADH and aldosterone it stimulate diuresis and thus improve urine output and decrease fluid volume.