Which of the following structures is NOT a portion of a nephron?
a. vasa recta
b. nephron loop (loop of Henle)
c. distal convoluted tubule
d. proximal convoluted tubule
The correct answer and explanation is:
The correct answer is a. vasa recta.
The nephron is the functional unit of the kidney and is involved in the process of filtering blood, removing waste products, and maintaining fluid and electrolyte balance. A nephron consists of several key structures: the renal corpuscle, which includes the glomerulus and Bowman’s capsule, and the renal tubule, which includes the proximal convoluted tubule (PCT), nephron loop (loop of Henle), and distal convoluted tubule (DCT). These components play important roles in filtration, reabsorption, and secretion.
The vasa recta, however, is not a part of the nephron. It is a specialized network of blood vessels that is closely associated with the nephron. The vasa recta forms part of the countercurrent exchange system and is found primarily in the juxtamedullary nephrons. The vasa recta surrounds the loop of Henle and helps maintain the osmotic gradient in the renal medulla, which is essential for the kidney’s ability to concentrate urine. Although the vasa recta is crucial in the function of the nephron, it is not technically a structural component of the nephron itself.
To summarize, while the nephron loop, distal convoluted tubule, and proximal convoluted tubule are all direct components of the nephron involved in various stages of urine formation, the vasa recta is a blood vessel network involved in the transport of nutrients and waste but is not considered part of the nephron.