Metabolism
involves two major processes - (i) synthesis of compounds, known as anabolism
or (ii) breakdown of compounds called as catabolism. In a biological
system, breakdown of compounds produces products which are either utilised by
the body for various purposes or consumed in a reaction or removed from the
body. The breakdown of proteins, in particular and other nitrogenous
compounds, which are not utilised by the body for repair, growth or synthesis,
produce the so called " waste materials". These waste
materials are actually the breakdown products of proteins forming
various kinds of nitrogenous compounds viz. urea, ammonia, uric acid and
creatinine. These are called as nitrogenous waste products. They cannot
remain in the body for long because they are highly toxic and therefore must
be removed from the body. This process of removal of nitrogenous wastes from
the body is known as excretion. Further, the removal of these
wastes requires water. The amount of water required varies with the type
of nitrogenous compound excretion. Further, the removal of these wastes
requires water. The amount of water required varies with the type of
nitrogenous compound excreted, e.g., removal of ammonia requires lot of
water. Therefore, organisms living in water or aquatic organisms produce
this as a waste product and are known as ammontelic organisms. The
animals living on land, the terrestrial animals who need to
conserve water, however, excrete uric acid or urea and are therefore called as
uricotelic or ureotelic organisms respectively, depending upon the nature
of excretory product. Uric acid required very little water during excretion
while urea requires moderate amount. Thus, fishes are ammonotelic whereas
reptiles snakes and lizards) and birds are uricotelic and mammals
including man are ureotelic in nature.
Excretory Structures in different animals
1. Diffusion trough cell membrane amoeba, sponge, etc.
2. Nephridia - earthworm
3. Flame cells -Flat worms
4. Malapighian tubules - lnsects
5. Kidneys -Man
In the animal world, there are many different types of organs of excretion ivz, flame cells, or malpighian tubules i lower animals and kidneys in human beings. The nitrogenous wastes are removed from body in man, in the form urine, effected by kidneys.
Excretory Structures in different animals
1. Diffusion trough cell membrane amoeba, sponge, etc.
2. Nephridia - earthworm
3. Flame cells -Flat worms
4. Malapighian tubules - lnsects
5. Kidneys -Man
In the animal world, there are many different types of organs of excretion ivz, flame cells, or malpighian tubules i lower animals and kidneys in human beings. The nitrogenous wastes are removed from body in man, in the form urine, effected by kidneys.
No comments:
Post a Comment