Which of the following components is primarily reabsorbed in the proximal convoluted tubule of the nephron?

• A. Creatinine
• B. Glucose
• C. Bilirubin
• D. Urea

Answer: (B)

Verified step by step guidance

1. Understand the function of the proximal convoluted tubule (PCT): The PCT is the first segment of the nephron where most reabsorption occurs. It is responsible for reabsorbing essential substances like glucose, amino acids, ions, and water from the filtrate back into the bloodstream.
2. Identify the substances listed in the problem: Creatinine, glucose, bilirubin, and urea. Determine which of these substances are typically reabsorbed in the PCT.
3. Recall that glucose is actively reabsorbed in the PCT through sodium-glucose co-transporters (SGLTs). This process ensures that glucose is not lost in the urine under normal physiological conditions.
4. Note that creatinine is not reabsorbed in the PCT; it is primarily excreted as a waste product. Similarly, bilirubin is not reabsorbed in the nephron, as it is processed by the liver and excreted in bile. Urea is partially reabsorbed in the nephron, but this occurs later in the loop of Henle and collecting ducts, not primarily in the PCT.
5. Conclude that glucose is the correct answer because it is actively and primarily reabsorbed in the proximal convoluted tubule of the nephron.