When pH of the blood is too low, the ions secreted into the nephron from the surrounding capillaries are

Explanation:

• The pH of the blood is tightly regulated by the body to remain within a narrow range (approximately 7.35 - 7.45) for the proper functioning of enzymatic and physiological processes.
• When the blood pH becomes too low (a condition known as acidosis), the body employs various mechanisms to restore normal pH levels, including actions by the kidneys.
• When the blood pH is too low, the kidneys secrete hydrogen ions (H+) or convert ammonia (NH₃) into ammonium ions (NH₄+) and excrete them into the nephron for elimination.
• This mechanism helps to reduce acidity in the blood and restore its normal pH.
• The secretion of H⁺ and NH₄+ into the nephron is a compensatory response to acidosis, as these ions represent excess acid in the body.

Other Options:

• HCO₃-: Bicarbonate ions (HCO₃-) are reabsorbed into the bloodstream during acidosis, as they act as a buffer to neutralize excess hydrogen ions. Secreting HCO₃- into the nephron would worsen the acidosis, so this option is incorrect.
• Cl^-: Chloride ions (Cl-) are not directly involved in the regulation of blood pH under normal physiological conditions
• Na+: Sodium ions (Na⁺) are primarily involved in maintaining electrolyte balance, blood pressure, and fluid balance.