Excretory System

Lesson

Part 1 — getting rid of the wastes that our own cells make.

In this lesson you will

Concept

Excretory organs

Excretion is the removal of metabolic wastes made by body cells. Passing out undigested food is egestion, not excretion.

Table of four excretory organs and the wastes each removes
Organ	Wastes removed
Kidneys	Urea, excess water and salts (in urine)
Lungs	Carbon dioxide and water vapour
Skin	Water, salts and a little urea (in sweat)
Liver	Bile pigments from old red cells (in bile); makes urea

Check your understanding

The lungs act as excretory organs because they remove…

Multiple choice1 mark

The lungs act as excretory organs because they remove