Biology · Excretory Products and Their Elimination · NEET
| Loop of Henle | Short, barely enters medulla | Long, runs deep into medulla |
| Vasa recta | Absent or highly reduced | Well developed |
| Renal corpuscle position | In outer cortex | Near cortex-medulla junction |
| Number | Majority of nephrons | Fewer (some nephrons) |
| Role in concentrating urine | Little role | Main role (sets up gradient) |
Juxtamedullary nephrons have the long loop of Henle. NCERT says: in the majority of nephrons the loop of Henle is too short and extends only very little into the medulla — these are cortical nephrons; in some nephrons the loop is very long and runs deep into the medulla — these are juxtamedullary. Students often reverse this in exams, so lock it: JUXTAmedullary = long and deep.
The vasa recta (the U-shaped capillary running parallel to the loop of Henle) is well developed only in juxtamedullary nephrons. In cortical nephrons the vasa recta is absent or highly reduced. This is why the juxtamedullary type is essential for building the medullary concentration gradient.
Juxtamedullary nephrons. Their long loop of Henle plus vasa recta run deep into the medulla and, through the counter current mechanism, help maintain the osmolarity gradient (300 to 1200 mOsmol/L). This gradient lets the collecting duct pull out water and produce concentrated urine. Cortical nephrons, with short loops and reduced vasa recta, contribute little to this.
Yes. NCERT states the loop is short in the MAJORITY of nephrons, which are the cortical type. Only SOME nephrons are juxtamedullary. So cortical nephrons outnumber juxtamedullary nephrons — the reverse is a common NEET trap option.
'Juxta' means 'next to' or 'near'. A juxtamedullary nephron has its renal corpuscle (Malpighian body) sitting near the boundary of the cortex and medulla, close to the medulla, so its long loop can dive deep into the medulla. Do not confuse this with the juxtaglomerular apparatus (JGA), which is a different structure near the glomerulus.
Assertion (A): Nephrons are of two types: Cortical & Juxta medullary, based on their relative position in cortex and medulla. Reason (R): Juxta medullary nephrons have short loop of Henle whereas, cortical nephrons have longer loop of Henle. In the light of the above statements, choose the correct answer:
Choose the correct statement given below regarding juxta medullary nephron.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Loop of Henle length and vasa recta. Cortical nephrons have a short loop that barely enters the medulla and little or no vasa recta. Juxtamedullary nephrons have a long loop that runs deep into the medulla with a well-developed vasa recta.
Cortical nephrons. NCERT says the loop of Henle is short in the majority of nephrons, so cortical nephrons form most of the total, while only some are juxtamedullary.
Their long loop of Henle and vasa recta set up the counter current mechanism and the medullary osmolarity gradient (300 to 1200 mOsmol/L). This gradient is needed to produce concentrated urine and conserve water.
No. In cortical nephrons the vasa recta is absent or highly reduced. It is well developed only in juxtamedullary nephrons.
In both types the renal corpuscle (Malpighian body) lies in the cortex. In juxtamedullary nephrons it sits deeper, near the cortex-medulla junction, so the long loop can extend into the medulla.
