Describe/ explain the role of mammalian kidney/ nephron in homeostasis.

-When the osmotic pressure of the blood rises above normal (as a result of dehydration); the osmoreceptors in the hypothalamus are stimulated; which stimulates the pituitary gland to secrete a hormone called Anti-diuretic hormone (ADH) or vasopressin into the blood;
-On reaching the kidney, Anti-diuretic hormone (ADH) or vasopressin causes the kidney tubules to be more permeable to water; more water is reabsorbed into the blood stream lowering osmotic pressure of the blood; producing a concentrated urine.
-When the osmotic pressure of the blood falls below normal, hypothalamus is less stimulated; hence the pituitary gland is less stimulated; less Anti-diuretic hormone (ADH) or vasopressin is released into the blood stream;
-The kidney tubules become less permeable to water; and less re-absorption of water into blood stream takes place; hence osmotic pressure of blood rises and dilute urine is produced;
-When the level of sodium ions is low in the blood; adrenal glands are stimulated to release aldosterone into the blood; Aldosterone stimulate loop of Henle of kidney to reabsorb sodium ion into the blood;
-If the sodium ions concentration in the blood rises above optimum level, adrenal glands produce less aldosterone into the blood; and less amounts of sodium ions are absorbed;