Question

Which is true about the difference between cortical and juxtamedullary nephrons
(a) Most nephrons are juxtamedullary
(b) The efferent arterioles of cortical nephrons give rise to most of the vasa recta
(c) The afferent arterioles of juxtamedullary nephrons give rise to most of the vasa recta
(d) Juxtamedullary nephrons generate a hypo-osmotic medullary interstitium

Answer 1

Hint: filtration in the nephrons takes place due to osmotic pressure differences between lumen and interstitium by the countercurrent mechanism by vasa recta which is a peritubular network around Henle’s loop. Juxtamedullary nephrons contain a long loop of Henle

Complete answer:
The cortical region of the kidney consists of the Malpighian corpuscle, PCT, and DCT, and a loop of Henle is present in the medullary region. Loop of Henle is short in the majority of nephrons and they extend only a little into the medullary region. They are called cortical nephrons and in juxtamedullary nephrons, the loop of Henle is very long, so it runs deep into the medulla. Peritubular capillaries that surround the loop of Henle are called vasa recta. Well-developed vasa recta are present in the juxtamedullary nephrons. Due to the presence of long vasa recta in these neurons, they generate a hypo-osmotic pressure in the interstitium.

Additional information:
- Approximately 10 lakhs nephrons are present in each kidney and they are the structural and functional units containing bowman’s capsule, proximal convoluted tubules, Henle’s loop, distal convoluted tubule, and collecting duct.
- Kidney is divided into two regions, the cortical region, and the medullary region. Bowman’s capsule, PCT, and DCT are present in cortical regions and the loop of Henle is present in the medullary region.
- Based on the length and location of the loop on Henley, there are two types of nephrons: they are juxtamedullary nephrons and cortical nephrons.
- Vasa recta and nephrons generate osmotic differences in the lumen and interstitium.

So, the correct answer is ‘ juxtamedullary nephrons generate a hypo-osmotic medullary interstitium’

Note:
Filtration of blood from the glomerulus into the lumen of the Bowmans’ capsule is called glomerular filtration and this process is non-energy consuming(passive) and it is the first step in the formation of urine.
Vasa recta present in the renal system develop an osmotic different mechanism by counter-current mechanisms.