Biology
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Nephrons- Definition, Structure, Types, Difference

The human excretory system consists of a complex tubular structure inside its two bean shaped kidneys. In this blog, we will be understanding the structure of nephrons and its type.

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Posted by barisbilgic, 25/9/2021
Nephrons- Definition, Structure, Types, Difference

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In humans, the excretory system consists of a pair of kidneys, a pair of ureters, a urinary bladder and a urethra. The kidney which is a reddish-brown bean-shaped organ consists of a complex tubular structure called nephrons. Firstly, let us see its definition. Then, we will discuss the nephron structure, its function, different types along with their differences.

What are Nephrons?

The human excretory system consists of millions of complex tubular structures, known as nephrons. They are the structural and functional units of the kidney. It is an epithelial tube that is about 3 cm long and 20-60 mm in diameter.

Structure of Nephrons

Firstly, let us first see the structure of a nephron. Then, we will be discussing its various parts.

diagram of nephron
Fig. a. A diagrammatic representation of nephron structure.
Source: NCERT

So, as we can see nephrons are divided into four regions. These are:

Bowman’s capsule :

The proximal end of the nephron has a cup-shaped double-walled structure known as Bowman’s capsule. Thin flat cells called podocytes are present on their lining. Furthermore, a network of capillaries, called glomerulus is present within the Bowman’s capsule. Also, the glomerulus and Bowman’s capsule together form the Malpighian body (see fig. b) or renal corpuscle. It deals with the first step of urine formation i.e. filtration. Efferent arteriole carries away the blood from the glomerulus.

Proximal convoluted tubule (PCT) :

A highly coiled tubular structure, continuing from the renal tubule. The epithelial cells of this region are specialized for the transport of salts and other substances from the lumen to the interstitial fluid. The simple cuboidal brush border epithelium lines these proximal convoluted tubules.

Henle’s loop :

A hairpin or U-shaped structure called Henle’s loop starts after the PCT. This loop has a descending limb. It is further followed by an ascending limb that ends before the distal convoluted tubule.

Distal convoluted tubule (DCT) :

The ascending limb of Henle’s loop continues to form another tubular region, called the distal convoluted tubule. It is lined by cuboidal epithelial cells. The DCTs of several nephrons open into a straight tube called the collecting duct. Further, these ducts meet and open into the renal pelvis through medullary pyramids in the calyces.

Bowman's capsule and glomerulus i.e. malphigian body
Fig. b, Diagrammatic representation of Malpighian body or renal corpuscles.

Also, the Malpighian corpuscle, PCT and DCT of the nephron are present in the cortical region of the kidney that is, the renal cortex. Whereas, Henle’s loop and collecting duct are present in the renal medulla.

Furthermore, the efferent arteriole emerging from the glomerulus forms a fine capillary network around the renal tubule called the peritubular capillaries.

A minute vessel of this network runs parallel to Henle’s loop forming a ‘U’ shaped structure called as vasa recta.

Types of nephrons

There are two types of nephrons, namely:

  1. Cortical nephrons : Nephrons with short loop of Henle that extends very little into the medulla.
  2. Juxta medullary nephrons : Nephrons with very long loop of Henle which runs deep into the medulla.

Difference between cortical and juxta medullary nephron

Now let us see the differences between the above-mentioned types of nephrons.

Differences between the two types of nephrons.

So, with this we come to end of the blog. Check our Study Materials for other subjects to enhance your preparations. Happy learning! 🙂

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