Nephron: Definition and Meaning, Structure of Nephron, Types of Nephron

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Definition and Meaning of Nephron

It can be denied as the basic functional unit of kidneys that consists of a glomerulus and its associated tubules.
The glomerular filtrate passes through before it emerges as urine.
These are the microscopic structure composed of a renal corpuscle and a renal tubule.
In Greek, the word nephron means kidney.
Each human kidney consists of about millions of nephrons.

It is the initial filtering component.
It is the site of the filtration of blood plasma.
It consists of the glomerulus and the glomerular capsule or Bowman’s capsule.
A vascular pole and a tubular pole are the two poles.
At the renal tubule at the urinary pole, the glomerular filtrate leaves the Bowman’s capsule.
At the vascular pole, the arterioles from the renal circulation enter and leave the glomerulus.

It is a double-walled cuplike structure that makes up part of the nephron.
It is also known as Bowman capsule, glomerular capsule, renal corpuscular capsule, or capsular glomeruli.
It creates a urinary space through which filtrate can enter the nephron and pass to the proximal convoluted tubule.

Each glomerulus receives its blood supply from an afferent arteriole of the renal circulation.
The glomerular blood pressure provides:
- The driving force for water and solutes to be filtered out of the blood plasma.
- Into the interior of Bowman’s capsule, called Bowman’s space.
The rest passes into an efferent arteriole, only about a fifth of the plasma is filtered in the glomerulus.

It is the portion of the nephron containing the tubular fluid filtered through the glomerulus.
The filtrate continues to the collecting duct system after passing through the renal tubule.

Proximal convoluted tubule (lies in cortex and lined by simple cuboidal epithelium with brush borders.
- Help to increase the area of absorption.
Loop of Henle is the hairpin like, i.e. U-shaped, and lies in medulla.
The collecting duct system of the kidney consists of a series of tubules and ducts.
- Physically connect nephrons to a minor calyx.
- Directly to the renal pelvis.
- The collecting duct system is the last part of nephron and participates in electrolyte and fluid balance.

A portion of kidney nephron between the loop of Henle and the collecting tubule is called the distal convoluted tubule (DCT).

Juxtamedullary nephrons are found only in birds and mammals.
Juxtamedullary nephrons start low in the cortex near the medulla and have a long loop of Henle.
Cortical nephrons (many nephrons) start high in the cortex and have a short loop of Henle.
- Can be subdivided into superficial cortical nephrons and midcortical nephrons.