Describe the role of liver, lungs and skin in excretion



Role of liver : Liver secretes bile containing jj substances like bilirubin, biliverdin, cholestrol, degraded steroid hormones, vitamins and drugs, Most of these substances ultimately pass out along with digestive wastes.
Role of lungs : Lungs regularly remove some volatile materials, carbon dixoide and water as metabolic wastes produced during oxidation of food in cells. Lung remove the CO2 and some water as vapour in the expired air.
Role of skin: The sweat and sebaceous glands in the skin can eliminate certain substances through their secretions. Sweat produced by the sweat glands is a watery fluid containing NaCl, small amount of
urea, lactic acid, etc. Sebaceous glands eliminate certain substances like sterols, hydrocarbons and waxes through sebum. This secretion provide a protective covering for the skin.