In the kidneys, what is the primary function of the renal pelvis?

• A. Collects urine from the major calyces and funnels it into the ureter
• B. Reabsorbs most water and solutes back into the peritubular capillaries
• C. Filters blood plasma to form the initial filtrate
• D. Secretes erythropoietin to stimulate red blood cell production

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the anatomy of the kidney, focusing on the flow of urine from its formation to excretion. The kidney has structures such as nephrons, calyces, and the renal pelvis.
2. Step 2: Identify the role of the nephron, which is to filter blood plasma and form the initial filtrate. This eliminates options related to filtration and reabsorption at this stage.
3. Step 3: Recognize that reabsorption of water and solutes occurs primarily in the nephron tubules and peritubular capillaries, not in the renal pelvis.
4. Step 4: Know that erythropoietin secretion is a hormonal function of the kidney, but it is not related to the renal pelvis; it is secreted by specialized cells in the kidney cortex.
5. Step 5: Conclude that the renal pelvis acts as a funnel collecting urine from the major calyces and directing it into the ureter for transport to the bladder.