Question

How much percentage of cortical Nephrons comprise the kidney ?

• A. 90% - 95%
• B. 85% - 86%
• C. 70% - 75%
• D. 40% - 60%

Hint:

Always remember: Cortical = Common & Short (85%). Juxtamedullary = Rare & Long (15%). The long loops of the juxtamedullary nephrons are the secret to highly concentrated, yellow urine!

Answer 1

The Correct Option is B

Step 1: Concept:
The question tests microscopic renal anatomy, specifically the population distribution of the two distinct types of nephrons (the functional units of the kidney) found within the human renal system.

Step 2: Step-by-step Explanation:

• The human kidney contains approximately 1 to 1.5 million nephrons, which are broadly classified into two categories based on their anatomical location and the length of their Loop of Henle.

• 1. Cortical Nephrons: These constitute the vast majority of nephrons. Their renal corpuscles (glomeruli) are located high up in the outer renal cortex. They possess relatively short Loops of Henle that barely penetrate into the outer zone of the renal medulla. Cortical nephrons are primarily responsible for the bulk reabsorption of water and solutes, and they represent roughly 80% to 85% (up to 86%) of all nephrons in humans.

• 2. Juxtamedullary Nephrons: These constitute the minority. Their renal corpuscles are located deep in the cortex, adjacent to the medulla (juxta = next to). They have extremely long Loops of Henle that dive deep into the inner medulla. These specialized nephrons are crucial for establishing the medullary osmotic gradient required to concentrate urine, representing the remaining 15% to 20%.

• Among the provided options, 85% - 86% is the most medically accurate representation of the cortical nephron population.

Step 3: Final Answer:
Cortical nephrons comprise approximately 85% - 86% of the kidney.