In the kidney mechanism for buffering the acidity of the blood, when would hydrogen ions be excreted and bicarbonate ions be reabsorbed?
( ) only when the lung system is not working
( ) when the blood is acidic
( ) when the blood is basic
( ) when the blood is neutral ph, which is not normal
( ) the kidney never excretes or reabsorbs hydrogen and bicarbonate ions.

Explanation:

Kidneys along with filtration of blood maintain the homeostasis in the human body. The kidneys maintain the homeostasis by many mechanisms in which one of the mechanism is to maintain the acid-base balance in the blood.

When the pH of the blood drops below the 7.35 the blood becomes acidic in nature and a condition arises called acidosis. During acidosis, the Hydrogen ion concentration in the blood increases.

To overcome the acidosis, the kidneys excrete the hydrogen ions through the urine and absorb more bicarbonate from the tubular fluid through the tubules. The bicarbonate acts as a buffer and form carbonic acid with hydrogen ions. These hydrogen ions are excreted out with urine.

Thus, the selected option is the correct answer.

a- all cells come from pre-existing cells