Diagram of a Nephron (with Labels) Explained
A nephron is the functional unit of the kidney that filters blood to produce urine. Each kidney contains about one million nephrons. This labelled diagram
TL;DR: A nephron is the functional unit of the kidney that filters blood to produce urine. Each kidney contains about one million nephrons. This labelled dia…
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
Diagram of a Nephron (with Labels): A nephron is the functional unit of the kidney that filters blood to produce urine. Each kidney contains about one million nephrons. This labelled diagram
Diagram of a Nephron (with Labels) Explained Simply
A nephron is the functional unit of the kidney that filters blood to produce urine. Each kidney contains about one million nephrons. This labelled diagram This is a key Biology concept for Class 10.
Parts and Labels
The glomerulus is a network of capillaries inside Bowman's capsule where ultrafiltration occurs. Bowman's capsule (renal capsule) is a cup-shaped structure surrounding the glomerulus; it collects the filtrate. The proximal convoluted tubule (PCT) is a highly coiled tube where selective reabsorption of glucose, amino acids, and ions occurs. The loop of Henle is a U-shaped tube with a descending limb (permeable to water) and an ascending limb (actively transports ions but impermeable to water); it creates a salt gradient for water reabsorption. The distal convoluted tubule (DCT) is another coiled section where more selective reabsorption and secretion occur; it is also sensitive to hormones like ADH. The collecting duct collects filtrate from many DCTs; it is permeable to water (in presence of ADH) and performs final water reabsorption. The afferent arteriole brings blood from the renal artery to the glomerulus. The efferent arteriole carries blood away from the glomerulus with retained proteins and cells. The peritubular capillaries surround the convoluted tubules for reabsorption and secretion. The vasa recta are capillaries that run parallel to the loop of Henle.
How to Draw It
Step 1: Draw Bowman's capsule as a cup-shaped structure at the top. Step 2: Inside the capsule, draw the glomerulus as a tangled network of capillaries. Step 3: From Bowman's capsule, draw the proximal convoluted tubule as a coiled tube with many loops going downward. Step 4: From the PCT, draw the loop of Henle as a U-shaped tube descending (thin walls) then ascending (thick walls). Step 5: From the loop of Henle, draw the distal convoluted tubule as another coiled section. Step 6: From the DCT, draw the collecting duct as a straighter tube collecting filtrate. Step 7: Around the tubules, draw the peritubular capillary network. Step 8: Draw arterioles: afferent arteriole entering the glomerulus and efferent arteriole leaving. Step 9: Label all structures clearly. Step 10: Use arrows to show filtrate movement through the tubes and material reabsorption back into capillaries. Step 11: Use different colors or shading to distinguish between filtrate, reabsorbed materials, and blood.
Function
Blood enters the nephron through the afferent arteriole into the glomerulus. The high pressure in the glomerular capillaries forces small molecules (water, glucose, urea, ions) through the capillary wall into Bowman's capsule in a process called ultrafiltration. Large proteins and blood cells remain in the capillaries. The filtrate moves through the proximal convoluted tubule, where glucose, amino acids, and useful ions are selectively reabsorbed back into the peritubular capillaries. The loop of Henle creates a salt gradient, allowing further water reabsorption. The distal convoluted tubule reabsorbs more ions and water (controlled by ADH). The collecting duct performs final water reabsorption (controlled by ADH). The remaining filtrate, now called urine, contains excess water, urea, and other wastes. It moves to the collecting duct, then to the pelvis, ureter, and bladder for storage and eventual excretion.
Key Points to Remember
Ultrafiltration occurs in the glomerulus under high pressure. Selective reabsorption occurs in the proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct. The loop of Henle is the key structure for concentrating urine by creating a salt gradient. ADH (antidiuretic hormone) controls water permeability of the DCT and collecting duct. Most glucose, amino acids, and ions are reabsorbed; urea is mostly left in the filtrate. The vasa recta run alongside the loop of Henle, allowing exchange of dissolved substances in the interstitium.
Worked Examples
Example 1. Why are glucose and amino acids normally absent from urine even though they are filtered at the glomerulus?
Solution: Glucose and amino acids are small enough to pass through the glomerular filtration barrier and enter the filtrate. However, they are useful to the body, so they are selectively reabsorbed in the proximal convoluted tubule back into the peritubular capillaries. Normal urine contains neither because they are completely reabsorbed before reaching the collecting duct.
Example 2. Explain how ADH controls urine concentration.
Solution: ADH is secreted when blood osmotic pressure is high (dehydration). It makes the distal convoluted tubule and collecting duct permeable to water, allowing water reabsorption back into the blood. This produces small volumes of concentrated urine, conserving body water. Without ADH, more water remains in the filtrate, producing large volumes of dilute urine.
Where You See This in Real Life
- Diabetes mellitus causes excess glucose in the filtrate, which exceeds the reabsorption capacity of the PCT, resulting in glucose in urine
- Kidney stones form when certain substances precipitate out in the collecting duct or ureter, causing severe pain
- Chronic kidney disease damages nephrons, reducing the kidney's ability to filter waste and regulate water balance
- Excessive alcohol consumption increases urine output by inhibiting ADH secretion, which can lead to dehydration
Common Mistakes Students Make
- Forgetting that the loop of Henle has two distinct limbs with different properties: the descending limb is permeable to water; the ascending limb actively transports ions but is impermeable to water.
- Not understanding that proteins and blood cells DO NOT enter Bowman's capsule because they are too large to pass through the filtration barrier.
- Confusing selective reabsorption (useful substances returning to blood) with secretion (additional wastes being added to the filtrate).
- Placing the peritubular capillaries in the wrong location or forgetting their role in reabsorption and secretion.
Frequently Asked Questions
What is the difference between ultrafiltration and selective reabsorption?
Ultrafiltration in the glomerulus is a non-selective, high-pressure process forcing small molecules into Bowman's capsule. Selective reabsorption in the proximal convoluted tubule is an active, selective process returning useful substances (glucose, amino acids) back into the peritubular capillaries.
Why is the loop of Henle important for urine concentration?
The loop of Henle creates a salt gradient in the medulla. The descending limb loses water but gains salt; the ascending limb loses salt but gains no water (impermeable). This gradient allows the collecting duct to reabsorb water efficiently, producing concentrated urine while conserving body water.
What happens if a person's kidneys cannot produce concentrated urine?
They will produce large volumes of dilute urine and become dehydrated unless they drink compensatory amounts of water. This occurs in conditions like diabetes insipidus, where ADH production or kidney sensitivity to ADH is impaired.