Final answer:
The kidneys aid in maintaining acid-base balance by altering the absorption rates of sodium, potassium, and chloride ions, with sodium playing a particularly important role. The options (1), (2) and (4) are correct.
Step-by-step explanation:
The kidneys aid in acid-base balance by altering the rate of absorption of several ions, including sodium (Na+), potassium (K+), and chloride (Cl-). These ions play crucial roles in maintaining the pH balance in the body. For instance, the kidneys regulate blood pH by adjusting hydrogen ion levels and reabsorbing bicarbonate.
Sodium and chloride ions are especially important in this process, with sodium being reabsorbed or excreted in exchange for hydrogen or potassium ions, and chloride balancing positive ion charges. During acidosis, there is an increased excretion of sodium and chloride ions due to poor tubular reabsorption, while conserving more bicarbonate to neutralize the excess hydrogen ions. Therefore, options (1), (2), and (4) are correct.