Nephron: Definition and Meaning, Structure of Nephron, Types of Nephron (For CBSE, ICSE, IAS, NET, NRA 2022)

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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.
A Kidney Nephron and Its Structure

Structure of Nephron

  • It is the functional unit of Kidney.
  • The main work of the kidney is performed at each separate nephron.
  • It is made up of two parts a renal corpuscle and a renal tubule.

Renal Corpuscle

  • 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.

Bowman՚S Capsule

  • 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.

Glomerulus

  • 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.

Renal Tubule

  • 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.

Components of 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.
Collecting Duct System
Distal Convoluted Tubule
  • A portion of kidney nephron between the loop of Henle and the collecting tubule is called the distal convoluted tubule (DCT) .
Length Difference
  • 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.
Length Difference