- Nitrogenous substances carbondioxide, pigments, excess water, etc.
- The nitrogenous waste can be excreted in the following forms:
- Ammonia, Urea, Uric acid- conservation of water is needed. EXCRETORY SYSTEM OF MAMMALS
Left kidney is higher than the right kidney.
A kidney is composed of 1.2 million
microscopic structural and functional units
called nephrons or uriniferoustubules.
Act of passing urine is called Micturition.
* These animal excrete nitrogen in the form of ammonia, e.g., aquatic invertebrates Amoeba, Hydra, Prawn, Pila, and freshwater fishes Bony Fish, Frog’s tadpole. Ureotelic Animals
*They excrete nitrogen in the form of urea, e.g., mammal (man), frogs, toads, other amphibians and cartilaginous fishes like sharks.
* They excrete the nitrogenous wastes in the form of uric acid e.g., reptiles, snakes, lizards, crocodiles and birds.
Functional unit of kidney. It is a long tube differentiated into 4 regions.
- Bowman’s Capsule
The Bowman’s capsule and the glomerulus together
form a globular body called Malpighian body.
* The yellow colourof urine is caused by the
pigment urochrome, which is a breakdown
product of haemoglobinfrom worn out RBCs
* The urine on standing gives a pungent smell.
It is due to conversion of urea into ammonia
* pH of urine is between 5-8. Average pH is
6.0 (slightly acidic)
* kidney stones: Calcium Oxalate.