Question

Give a brief account of the accessory excretory organs and the substances removed by them.

Answer 1

1. Lungs: The lungs remove carbon dioxide produced during cellular respiration and also eliminate a certain amount of water vapour during exhalation.
2. Liver: The liver secretes bile containing bilirubin, alcohol, cholesterol, vitamins and certain drugs. These substances are removed along with the undigested food, and some are also excreted in the urine.
3. Skin: The sweat glands of the skin remove sweat containing salts, lactic acid and a small amount of urea. The main function of sweating is thermoregulation, but it also contributes to excretion.

Thus, the lungs, liver and skin act as accessory excretory organs.