Kidneys maintain the acid-base balance through two mechanisms,- the secretion of H+ ions and the reabsorption of bicarbonate HCO3 from urine which is then released into the blood. The regulation of H+ ions and bicarbonate HCO3 is determined by the concentration of the two released within the urine.
The kidneys control acid-base balance by secreting H+ ions and reabsorbing bicarbonate HCO3 from urine, with this substance being released into the bloodstream. The regulation of H+ ions and bicarbonate HCO3 depends on their concentrations in the urine.