AEMCA Practice Exam

What distinguishes the juxtamedullary nephron from the cortical nephron?

1. It is larger in size

2. It is located at the boundary of cortex and medulla

3. It has no loop of Henle

4. It functions only in the filtration process

The correct answer is: It is located at the boundary of cortex and medulla

The distinction of the juxtamedullary nephron from the cortical nephron is primarily based on its anatomical location. Juxtamedullary nephrons are situated at the boundary between the cortex and the medulla of the kidney. This positioning allows them to play a significant role in concentrating urine, as they possess longer loops of Henle that extend deep into the medulla. This structural feature facilitates the reabsorption of water and helps maintain the osmotic gradient necessary for the body's fluid balance. In contrast, cortical nephrons, which are more abundant, are primarily located in the renal cortex and have shorter loops of Henle. Their function is oriented more towards the process of filtration rather than the concentration of urine. The other choices do not accurately describe the characteristics that distinguish juxtamedullary nephrons. They are not larger in size than cortical nephrons, they do have a loop of Henle, and they participate in both filtration and additional processes related to concentration, rather than only filtration.