Describe the structure and functioning of nephrons.

Explanation

In addition to the kidneys, liver, lungs and skin also play an important role in the elimination of excretory wastes.
a) Liver : Liver in the largest gland in our body, secretes bile, containing substances like bilirubin, biliverdin, cholestrol, degraded steroid hormones, vitamins and drags. Most of these substances ultimately pass out along with digestive wastes.
b) Lungs : Lungs remove large amounts of `CO_(2)` (18 litres 1 day), various, volatile materials and significant quantities of water.
c) Skin : Human skin possesses two types of glands namely sweat and sebaceous glands for the elimination of certain substances through their secretions.
`star` Sweat produced by the sweat glands is a watery fluid containing NaCl, small amount of urea, lactic acid etc.,
`star` Sebaceous glands eliminate certain substances like sterols, hydrocarbons and waxes through sebum. This secretion provides a protective oily convering for the skin.