Everything About Nephrons, Its Parts And Functions You Need To Know

Tubular Structure Of Kidneys

Kidney is made up of closely arranged tubular structures may be called as uriniferous tubules. Blood vessels and interstitial connective tissues are interposed between these tubules.

Uriniferous Tubules:

Uriniferous tubules contains following parts:

  • Nephrons
  • Collecting Ducts

1- Nephrons:

The structural and functional unit of the kidney, known as nephron. Its main function is blood filtration resulting in urine formation. Each kidney contains 1 to 1.3 million nephrons. The number of nephron starts decreasing after about 45 years to 50 years of age.

Parts of Nephrons:

There are two parts of nephrons. These are!

  • Malpighian Corpuscle: It is a spheroidal and flattened structure with a diameter of 200 μm. Renal Corpuscle or Malpighian Corpuscle is further composed of two parts:
    • Bowman’s Capsule: A cup-shaped structure in nephrons, known as Bowman’s Capsule. It is formed by inner visceral layer and outer parietal layer. It encloses Glomerulus.
    • Glomerulus: It is a network of capillaries enclosed in Bowman’s capsule. It is formed by the division of afferent arteriole and then glomerulus joins to form efferent arteriole. Blood circulates within these blood vessels. When blood reaches the smallest blood vessels in glomerulus. Here it is filtered due to high blood pressure and waste materials are removed from blood and filtered blood enters efferent arteriole and leaves the glomerulus.
  • Renal Tubule: It is the part of nephron that starts after the Bowman’s Capsule. Renal Tubule consists of following parts:
    • Proximal Convoluted Tubule: It is the coiled portion that starts after Bowman Capsule. It is situated in the cortex. The length of proximal tubule is 14 mm and the diameter is 55 μ. Proximal Convoluted tubule continued as Loop of Henle.
    • Loop of Henle: Loop of Henle consists of three parts. These are Descending Limb, Hairpin bend and Ascending Limb.
    • Distal Convoluted Tubule: Distal convoluted tubule starts after the loop of Henle. It occupies the cortex of kidney. It is continued as collecting duct. The length of Distal convoluted tubule is 14.5 to 15 mm. It has a diameter of 22 to 50 μ.

2- Collecting Duct:

Distal convoluted tubule continues as the initial or arched collecting duct, which is in cortex of the kidney. The lower part of the collecting duct lies in the medulla. Seven to ten initial collecting ducts unite to form the straight collecting duct, which passes through medulla.

Length of collecting duct is about 20 to 22 mm. Its diameter varies between 40 and 200 μ. Collecting duct is made of cuboidal or columnar epithelial cells.

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