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Excretory Products and their Elimination

Excretory System In Humans (Group B)



  • 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 amphibians and aquatic insects

    • Such organisms are called ammonotelic.

  • Urea

    • Less toxic

    • Requires less water for excretion

    • Terrestrial adaptation for conservation of water

    • Ammonia Urea

    • Examples of organisms excreting urea: terrestrial amphibians and marine fishes

    • Such organisms are called ureotelic.

  • Uric acid

    • Least toxic

    • Eliminated with the least loss of water, as pellets or paste

    • Examples of organisms excreting uric acid: birds, reptiles, land snails and insects

    • Such organisms are called uricotelic.

Human excretory system

It comprises of: 

i. pair of kidneys

ii. pair of ureters

iii. urinary bladder

iv. urethra

  • Kidney is divided into outer cortex and inner medullary region.

  • Nephrons are basic fun…

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