Biology · Excretory Products and Their Elimination · NEET
The nephron is the functional unit of the kidney. Each human kidney has nearly one million nephrons, and each nephron has two parts: the glomerulus (a tuft of capillaries) and the renal tubule (Bowman's capsule, PCT, Henle's loop, DCT, and collecting duct). Memory hook: think "one million tiny filter machines" — the whole kidney is just this one part repeated a million times, which is exactly why NCERT calls the nephron the functional unit.
A single nephron: the glomerulus (in Bowman's capsule) filters blood, then the renal tubule (PCT, Henle's loop, DCT, collecting duct) processes the filtrate. The corpuscle, PCT and DCT sit in the cortex; only Henle's loop dips into the medulla. About one million such units make up each kidney.
Your doubts, answered
Is the nephron the structural unit or the functional unit of the kidney?
NCERT calls the nephron the functional unit of the kidney. It is the smallest part that can carry out the full job of the kidney on its own — filtration, reabsorption and secretion. Each kidney has nearly one million nephrons. So the whole kidney works because these one million nephrons work. In NEET, if an option says 'functional unit', choose nephron; do not confuse it with the tubule or glomerulus alone.
What are the two main parts of a nephron?
Every nephron has exactly two parts: (1) the glomerulus — a tuft of capillaries formed by the afferent arteriole, and (2) the renal tubule. The renal tubule begins with the Bowman's capsule (a double-walled cup) and continues as PCT, then Henle's loop, then DCT, and finally opens into a collecting duct. Remember: glomerulus + renal tubule = one nephron.
What is the difference between a nephron and a glomerulus?
A glomerulus is only one part of the nephron — it is the ball of capillaries where blood is filtered. The nephron is the complete unit: glomerulus PLUS the renal tubule. So the glomerulus is inside the nephron, not the same as it. The glomerulus together with the Bowman's capsule that surrounds it is called the Malpighian body (renal corpuscle).
Is Bowman's capsule part of the nephron?
Yes. Bowman's capsule is the very first part of the renal tubule, and the renal tubule is one of the two parts of the nephron. It is a double-walled cup-like structure that encloses the glomerulus. The glomerulus + Bowman's capsule together form the Malpighian corpuscle (renal corpuscle), which lies in the cortex of the kidney.
Which parts of the nephron lie in the cortex and which dip into the medulla?
The Malpighian corpuscle (glomerulus + Bowman's capsule), the PCT and the DCT lie in the cortical region. Only the loop of Henle dips down into the medulla. This is why juxtamedullary nephrons, which have a long loop of Henle running deep into the medulla, are important for making concentrated urine — a common NEET point.
⚠️ The NEET trap ✗ Choosing 'renal tubule' or 'glomerulus' when asked for the functional unit of the kidney. ✓ The nephron is the functional unit of the kidney. The tubule and glomerulus are only PARTS of the nephron. 🧠 Functional unit = the whole nephron, never just one of its parts. NCERT: 'nephrons... are the functional units.'
Real NEET questions
2018
Match the items given in Column I with those in Column II and select the correct option:
Column I (Function)
a. Ultrafiltration
b. Concentration of urine
c. Transport of urine
d. Storage of urine
Column II (Part of Excretory system)
i. Henle's loop
ii. Ureter
iii. Urinary bladder
iv. Malpighian corpuscle
v. Proximal convoluted tubule
A · a-v, b-iv, c-i, d-ii
B · a-iv, b-i, c-ii, d-iii ✓
C · a-iv, b-v, c-ii, d-iii
D · a-v, b-iv, c-i, d-iii
Solution: Ultrafiltration (a) happens at the Malpighian corpuscle (iv) — the glomerulus + Bowman's capsule part of the nephron. Concentration of urine (b) is by Henle's loop (i). Transport of urine (c) is by the ureter (ii). Storage of urine (d) is by the urinary bladder (iii). So the answer is a-iv, b-i, c-ii, d-iii. This tests whether you know which structural part of the nephron does which job.
2024
Choose the correct statement given below regarding juxta medullary nephron.
A · Renal corpuscle of juxta medullary nephron lies in the outer portion of the renal medulla.
B · Loop of Henle of juxta medullary nephron runs deep into medulla. ✓
C · Juxta medullary nephrons outnumber the cortical nephrons.
D · Juxta medullary nephrons are located in the columns of Bertini.
Solution: In juxtamedullary nephrons the loop of Henle is very long and runs deep into the medulla, so option B is correct. The renal corpuscle of every nephron lies in the cortex (not the medulla), so option A is wrong. Cortical nephrons are the majority, so juxtamedullary nephrons do NOT outnumber them (C wrong). Nephrons are not located in the columns of Bertini (D wrong). This checks whether you know where each part of the nephron sits.
2016
The part of nephron involved in active reabsorption of sodium is
A · Distal convoluted tubule
B · Proximal convoluted tubule ✓
C · Bowman's capsule
D · Descending limb of Henle's loop
Solution: The proximal convoluted tubule (PCT) is the part of the nephron that carries out active reabsorption of sodium. The PCT has a brush-border epithelium that increases surface area and reabsorbs nearly all nutrients and 70-80% of electrolytes and water. Bowman's capsule only filters, and the descending limb of Henle's loop is mainly permeable to water — so B is correct.
Solved Excretory Products and Their Elimination NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Each human kidney has nearly one million (about 10 lakh) nephrons. These are complex tubular structures and are called the functional units of the kidney.
What is the Malpighian body or renal corpuscle?
The glomerulus together with the Bowman's capsule that encloses it is called the Malpighian body or renal corpuscle. It lies in the cortex and is where blood filtration (ultrafiltration) begins.
What is the correct order of parts of the renal tubule?
Bowman's capsule -> proximal convoluted tubule (PCT) -> Henle's loop (descending then ascending limb) -> distal convoluted tubule (DCT) -> collecting duct. The DCTs of many nephrons open into a common collecting duct.
Which arteriole forms the glomerulus and which carries blood away?
The afferent arteriole (a fine branch of the renal artery) forms the glomerulus, and the efferent arteriole carries blood away from the glomerulus. The afferent is wider than the efferent, which helps build the pressure needed for filtration.
Why is the nephron called the functional unit and not the structural unit?
Because a single nephron can perform the complete kidney function — filtration, reabsorption and secretion — on its own. The kidney is simply about one million such units working together, so the nephron is the smallest fully functional part.
