Question

Which of the following diagrams is correct with regard to the proximal (P) and distal (D) tubule of the Nephron.

Options

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Answer 1

Explanation:

In the proximal convoluted tubule (PCT), the following processes occur:

• Reabsorption of Na⁺, Cl⁻, HCO₃⁻, and H₂O.
• Secretion of H⁺ and NH₃ (ammonia).

In the distal convoluted tubule (DCT):

• Reabsorption of Na⁺, CI⁻, HCO₃⁻, and H₂O.
• Secretion of H⁺ and K⁺ (important for acid-base balance).

Option (2) accurately represents these movements of ions and water in both tubules. It shows reabsorption of useful ions and water and secretion of H⁺ and NH₃ in the proximal and of K⁺ and H⁺ in the distal, matching physiological processes.