Biology · Excretory Products and Their Elimination · NEET
The afferent arteriole brings blood INTO the glomerulus, and the efferent arteriole carries blood OUT of it. NCERT states it plainly: the glomerulus is a tuft of capillaries formed by the afferent arteriole (a fine branch of the renal artery), and blood from the glomerulus is carried away by an efferent arteriole. Simple hook: Afferent = Arrives, Efferent = Exits.
The efferent (out-going) arteriole has a smaller diameter than the afferent (in-coming) arteriole. Because the exit is narrower than the entry, blood cannot leave the glomerulus as fast as it comes in. This builds up high hydrostatic (blood) pressure inside the glomerular capillaries, and that pressure is what pushes water and small solutes through the filtering membrane. This is why filtration in the kidney is called ultrafiltration under pressure.
The AFFERENT arteriole is part of the JGA, not the efferent. NCERT says the JGA is formed by cellular modifications in the distal convoluted tubule (DCT) and the afferent arteriole at the point where they touch. This is a very common NEET trap. The modified smooth-muscle cells in the afferent arteriole wall are the JG cells that release renin when GFR falls. Remember: JGA = DCT + afferent arteriole.
No. In a normal capillary bed, blood enters through an arteriole and leaves through a venule. In the glomerulus, blood enters through the afferent arteriole and leaves through another arteriole (the efferent), not a venule. This unusual arteriole-to-arteriole arrangement lets the kidney keep high pressure inside the glomerulus for filtration. The efferent arteriole then breaks up again into the peritubular capillaries and vasa recta around the tubule.
The efferent arteriole does not connect to a vein directly. It divides again into a second capillary network around the renal tubule called the peritubular capillaries; in juxtamedullary nephrons this includes the hairpin-shaped vasa recta that runs alongside the loop of Henle. These capillaries take back (reabsorb) useful substances and finally drain into the venous system.
The JGA (Juxta Glomerular Apparatus) is a special sensitive region formed by cellular modifications in _______ related to the same nephron.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
The afferent arteriole brings blood into the glomerulus and is wider; the efferent arteriole carries filtered blood out and is narrower. The narrow exit builds the pressure needed for filtration.
The afferent arteriole. The JGA is formed by the DCT and the afferent arteriole where they touch, and the JG cells there release renin.
Because the efferent arteriole (exit) is narrower than the afferent arteriole (entry), blood leaves slower than it arrives. This causes high hydrostatic pressure that drives ultrafiltration.
The glomerulus is a tuft of capillaries formed by the afferent arteriole, which is a fine branch of the renal artery. Blood is carried away from it by the efferent arteriole.
No. It leaves through the efferent arteriole (another arteriole, not a venule). The efferent arteriole then forms the peritubular capillaries and vasa recta before reaching veins.
