Describe the role of liver, lungs and skin in excretion.
Organs like lungs , liver and skin also play a role in excretion.
Lungs - Lungs remove large amounts of carbon dioxide and significant amount of water everyday.
Liver - The liver helps in the excretion of cholesterol, steroid hormones, vitamins, drugs, and other waste materials through bile. Urea is formed in the liver by the ornithine cycle. Ammonia - a toxic substance - is quickly changed into urea in the liver and thence eliminated from the body. Liver also changes the decomposed haemoglobin pigment into bile pigments called bilirubin and biliverdin.
Skin - Skin plays a major role in excretion of water, NaCl and small amounts of urea, lactic acid, etc. The sebaceous glands in the skin help eliminating substances like sterol, hydrocarbons, and waxes through sebum.
