Which part of the nephron is primarily responsible for the reabsorption of water and solutes from the filtrate?

• A. Proximal convoluted tubule
• B. Collecting duct
• C. Distal convoluted tubule
• D. Glomerulus

Answer: (A)

Verified step by step guidance

1. Understand the function of each part of the nephron: The nephron is the functional unit of the kidney, and its components include the glomerulus, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct. Each part has a specific role in filtration, reabsorption, and secretion.
2. Review the role of the proximal convoluted tubule: This segment is primarily responsible for the reabsorption of water, ions (like sodium and chloride), and nutrients (like glucose and amino acids) from the filtrate back into the bloodstream. Approximately 65-70% of the filtrate is reabsorbed here.
3. Examine the role of the collecting duct: The collecting duct is involved in the final concentration of urine. It reabsorbs water under the influence of antidiuretic hormone (ADH) but is not the primary site for reabsorption of solutes and water.
4. Analyze the distal convoluted tubule: This segment fine-tunes the reabsorption of ions like sodium and calcium and is involved in secretion, but it is not the primary site for water and solute reabsorption.
5. Clarify the role of the glomerulus: The glomerulus is responsible for filtration, not reabsorption. It filters blood to form the initial filtrate, which then enters the proximal convoluted tubule for reabsorption.