Question : Describe the role of liver, lungs and skin in excretion.

1.	Question : Describe the role of liver, lungs and skin in excretion.
Answer» Solution :(i) Role of liver in excretion : It helps in formation of bile pigments and urine pigment urochrome from Hb of dead RBCS. It changes excess of anmino acids into urea by Ornithine cycle by deamination and detoxification. (ii) Role of lungs : It helps in not only expelling foul air with more `CO_(2)` during expiration but ALSO to expel about 400 ml. of water per day. (iii) Role of SKIN : Sweat glands of skin expel water, inorganic salts like sodium chloride, lactic acid, some urea and `CO_(2)` in the form of sweat which helps in excretion and HOMEOTHERMY as evaporation of sweat gives cooling effect. Oil glands of skin expel waxes, sterols, fatty acids and a number of HYDROCARBONS in the form of sebum.

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