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Excretory Products and their Elimination

Excretory System In Humans (Group B)

  • Kidneys

    • Location: Between levels of the last thoracic and the third lumbar vertebra

    • Measurement: 10−12 cm (length) × 5−7 cm (width) × 2−3 cm (thickness)

    • Weight: 120−170 g

    • Hilum: A notch present towards the centre of the inner concave surface of the kidney

    • Through the hilum, the ureter, blood vessels and nerves enter the kidney.

    • On the inside of the hilum, the renal pelvis is present. Renal pelvis has projections called calyces.

    • 2 zones in the kidney: Cortex (outer)
      Medulla (inner)

    • Medulla divides into medullary pyramids (cone-shaped). These medullary pyramids project into the calyces.

    • Cortex is present in between the medullary pyramids as renal columns called the columns of Bertini.

    • Each kidney consists of about 1 million nephrons. These are the structural and functional units of the kidneys.

 

 

Excretion

  • Removal of nitrogenous wastes from the body

Nitrogenous wastes

  • Ammonia

    • Most toxic

    • Needs more water for getting excreted

    • Diffuses across general body surfaces

    • Examples of organisms excreting ammonia: fishes, aquatic…

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