Question

The mechanism of uric acid excretion in a nephron is

• A. Osmosis.
• B. Diffusion.
• C. Secretion.
• D. Ultrafiltration.

Answer 1

The correct option is C Secretion.

The pressure of the blood inside the glomerulus is increased due to the difference in diameter of the incoming and outgoing arterioles. This increased blood pressure helps to force most of the water, salts, glucose and urea of the blood out of the glomerular capillaries. This is the process of ultrafiltration. Tubular secretion removes excessive quantities of certain dissolved substances from the body, and also maintains the blood at a normal healthy pH. The substances that are secreted into the tubular fluid for removal from the body include potassium ions ($K^{+}$), hydrogen ions ($H^{+}$), ammonium ions ($N{H}_4^{+}$), creatinine, uric acid, some hormones and some drugs (e.g. penicillin). Hence the actual process which excretes out uric acid is through tubular secretion. So, the correct answer is option C.