Explain maintaining the pH Balance
You must be aware of the term pH. PH we know provides a measure on a scale from 0 to 14 of the acidity or alkalinity of a solution (where 7 is neutral and greater than 7 is basic (alkaline) and less than 7 is acidic). It is essential that the body maintains an optimum pH of 7.4 and kidneys do play a major role in ensuring that. Let us see how. The kidneys can correct any imbalances by removing excess acid (hydrogen ion) or base (bicarbonate) in the urine and restoring the bicarbonate concentration in the blood to normal. The tubular cells produce a constant amount of hydrogen ions and bicarbonate ions because of their own cellular metabolism (production of carbon dioxide).
By a carbonic anhydrase reaction identical to the red blood cells, hydrogen ions get produced and secreted into the lumen of the nephron. As well, bicarbonate ions get produced and secreted into the blood. In the lumen of the nephron, filtered bicarbonate combines along with the secreted hydrogen ions to form carbon dioxide and water (carbonic anhydrase is as well present on the luminal surface of the kidney cells). If the kidney eliminates hydrogen ions or bicarbonate ions in the urine relies upon the amount of bicarbonate filtered in the glomerulus from the blood relative to the amount of hydrogen ions secreted by the kidney cells. While the amount of filtered bicarbonate is greater than the amount of secreted hydrogen ions, then bicarbonate is lost in the urine. Likewise, if the amount of secreted hydrogen ion is greater than the amount of filtered bicarbonate, then hydrogen ions will be lost in the urine (i.e. acidic urine).