The glomerulus is located between the afferent arteriole and which of the following secondary resistant vessels?
a. peritubular capillaries
b. arcuate artery
c. efferent arteriole
d. renal vein
The correct answer and explanation is:
Correct Answer: c. efferent arteriole
Explanation (300 words)
The glomerulus is a key structure within the nephron of the kidney, playing a critical role in the filtration of blood to form urine. It is a cluster of capillaries located within the Bowman’s capsule, and it is uniquely positioned between two arterioles — the afferent arteriole and the efferent arteriole.
Afferent and Efferent Arterioles:
- The afferent arteriole delivers oxygenated blood into the glomerulus.
- The efferent arteriole carries the filtered blood away from the glomerulus.
This arrangement is unique in the body because most capillary beds are located between an arteriole and a venule, not between two arterioles. This setup creates a high-pressure system, which is essential for the process of glomerular filtration. The pressure difference facilitates the movement of water and solutes from the blood into the Bowman’s capsule.
Why not the other options?
- a. Peritubular capillaries: These are downstream of the efferent arteriole. They surround the tubular parts of the nephron and are involved in reabsorption and secretion, not in filtration.
- b. Arcuate artery: This is an artery located in the cortex of the kidney that gives rise to interlobular arteries. It is upstream of the afferent arteriole.
- d. Renal vein: This is part of the venous return system that ultimately drains filtered blood from the kidney, far downstream of the glomerulus.
Conclusion:
The efferent arteriole is the secondary resistant vessel that follows the glomerulus. Its smaller diameter compared to the afferent arteriole helps maintain the high glomerular hydrostatic pressure necessary for effective filtration.
Thus, the glomerulus is located between the afferent arteriole (incoming) and the efferent arteriole (outgoing).
✅ Correct answer: c. efferent arteriole.