regulating total water volume and total solute concentration
regulating ion concentrations in extracellular fluid
ensuring long-term acid-base balance
excreting metabolic wastes, toxins, drugs
The kidneys also:
produce erythropoietin and renin
activate vitamin D
go through the process of gluconeogenesis
after water intake, moistening of the mouth and throat mucosae and activation of stretch receptors in the stomach and intestine send signals that inhibit the thirst center.
after thirst is quenched a decrease in plasma osmolality causes the kidneys to begin eliminating excess water.
Inhibition of the release of the hormone ADH leads to excretion of large volumes of dilute urine
regulation of water balance by kidney activity is closely related to Na+ ion concentration.
Uncontrollable water losses in urine are called obligatory water losses
to maintain blood homeostasis, the kidneys must excrete a minimum of 500 mL of water per day to get rid of about 600 mmol of water-soluble solutes
