What is Excretion?

Question 1

What is metabolism?

Answer 1

Metabolism refers to the various chemical processes taking place in our body.

Question 2

What is excretion?

Answer 2

Excretion refers to the process by which metabolic wastes, toxins and other substances, in excess of requirement, are removed.

For example, carbon dioxide is excreted during exhalation, or sweat from the skin.

Question 3

What are the functions of the excretory system?

Answer 3

1. Controlling ion levels -
   Kidneys decide the amount of ions (e.g. sodium) we excrete in urine.
2. Excreting urea -
   Kidneys remove poisonous urea from the body in urine. This urea is a product of the breakdown of proteins by the liver.
3. Water control -
   The kidneys control how much water is lost in urine and how much is retained in the blood

Question 4

Why is important for humans to excrete?

Answer 4

If human beings don’t excrete, the toxic water products can build up in the body and prevent cells from working properly. This can damage the body and its functions.

Question 5

What are the types of nitrogenous waste?

Answer 5

Ammonia, Urea and Uric Acid

Question 6

Differentiate between excretion and egestion.

Answer 6

Excretion refers to the process by which metabolic waste is removed from an organism. In vertebrates, this is mainly carried out by the lungs, kidneys and skin. In mammals, urine is expelled through the urethra.

Egestion refers to the process by which undigested material (food), from a cell (in case of a unicellular organism), or from the digestive tract by the anus (in case of a multicellular organism) is discharged or expelled.

Question 7

Mention what the kidneys, skin, liver and lungs excrete respectively.

Answer 7

Kidneys - excess salt, water and nitrogenous waste
Skin - excess salt and water
Liver - nitrogenous waste products (ammonia, urea and uric acid), which result from protein degradation.
Lungs - carbon dioxide