The kidneys balance the pH by removing dietary acids from the blood thus making it more alkaline. If the urine is more acidic that means that the kidneys have regulated the reabsorption of carbonic acid in the tubule.
The kidneys produce a hormone called aldosterone that helps the body regulate blood pressure. Since they filter blood from the arteries damaging the said arteries will lead to kidney damage so to stay intact the kidneys help regulate the blood pressure that damages the arteries
