Monday, February 29, 2016
CONCEPT OF EXCRETION-TEXT
Excretion is the elimination of wastes that are formed during the metabolism of various substances in the body.
The main substances excreted are nitrogenous substances like Ammonia, Urea and Uric acid. Nitrogenous wastes are formed in the metabolism of amino acids and nucleic acids.
Along with these excess water, certain salts and organic substances are also excreted. The main purpose of excretion is to maintain ionic balance in the body.
If the metabolic wastes are not discharged from the body, they become toxic and harm the body.
All the animals do not excrete the type of nitrogenous wastes.
Some animals, like crabs excrete ammonia, while frogs and man excrete urea, insects, reptiles and birds excrete uric acid.
The type of the product excreted may change during different stages of development and availability of water.
Aquatic animals prefer to excrete ammonia while animals like reptiles and birds, to whom water is very scarce, excrete uric acid.