Nephron: The Functioning Unit of The Kidney

Each of our kidneys contains over a million nephrons.  They are the functioning unit of the kidneys. They remove waste from the body and produce urine. Each nephron is made up of two parts: a renal corpuscle and renal tubules (Figure 1).

Schematic diagram of the nephron demonstrating the site of action of diuretics. Source: PostGraduate Medical Journal
Figure 1. Schematic diagram of the nephron demonstrating the site of action of diuretics. Source: PostGraduate Medical Journal

Renal Corpuscle

  • This is the head of the nephron and it is where urine first forms.
  • It consists of the glomerulus, which is surrounded by the Bowman’s capsule (figure 2).
  • The glomerulus is like a network of capillaries. It look somewhat like a roll of yarn. The Bowman’s capsule, around the glomerulus, shapes like a funnel.
  • Blood is filtered across the glomerular capillaries into Bowman’s space. This is the first step in the formation of urine. Filtrates then exits the Bowman’s space into the renal tubules
  • Each renal corpuscle has  two poles:

(a) Vascular pole: this is where afferent arteriole enters the glomerulus and where efferent arterioles leave the glomerulus;

(b) Urinary pole: this is the area where filtrates produced by the glomerulus exits and enters the first part of the tubule.

The basic steps in urine formation  involves filtration of blood in the glomerulus, reabsorption, and secretion of wastes.
Basic steps in urine formation.

Renal Tubule

  • Filtrates from the glomerulus enters the tubules where urine continually forms.
  • The tubule begins at the Bowman’s capsule and consists of various segments (Figure 1):
  1. Proximal convoluted tubule
  2. Proximal straight tubule
  3. Loop of Henle contains:
    • thin descending limb
    • thin ascending limb
    • thick ascending limb
  4. Distal convoluted tubule
  5. The collecting ducts
  1. Reabsorption
  2. Secretion
  3. Excretion

We will discuss the various section of the tubules in part 2 of the Nephrons.

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  1. i love your videos
    i feel like your were sent from heaven to help me pass my exams
    please make some on the nepron and selective absorption and all that.

    also spermatozoa and all that stuff please

  2. yeah, your videos are of great help to all medical aspirants. i am finding it very easy now to learn after watching these videos. thank you. i would request you to upload more videos regarding human physiology which haven’t been uploaded.

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