Excretory Organs (Leaving Cert Biology): Revision Notes
📚Revision Notes
Excretory Organs
The main organs of excretion are:
- The lungs (water and CO₂)
- The skin (water and salts)
- The kidneys (urea, salt and water) These excretory organs maintain homeostasis.
Note
Excretion is the removal of metabolic wastes from the body.
These excretory organs help to:
- Regulate body temperature
- Control osmosis
- Control the concentration of body fluids
- Remove the waste products of metabolic reactions.
Note
Homeostasis: the maintenance of a constant internal environment.
Note
Metabolism: The sum of all the chemical reactions in the body.
Note
Exam Tip Excretion vs Egestion One of the common areas of confusion for students is the difference between excretion and egestion.
- Excretion is the removal of metabolic wastes from the body. These wastes include substances like urea, carbon dioxide, and salts, which are by-products of the body's metabolic processes.
- Egestion is the removal of undigested food waste from the body. This is not the same as excretion, as it involves the elimination of materials that were never absorbed into the body's cells.