1. 1. The respiratory system is responsible for supplying the body with oxygen
and removing carbon dioxide.
2. air enter the lungs following a definite pathway.
Nose = trachea = bronchi = bronchioles = alveoli
3. Air is forced into the lungs when the thoracic cavity expands and its air
pressure is reduced.
4. Air is forced out of the lungs when the thoracic cavity contracts and the air
Pressure on the lungs is increased.
5. Diffusion is the movement of a substance such as a gas from a place of
high concentration to a place of lower concentration.
6. Oxygen diffuses from the alveoli in the lungs into the blood capillaries
surrounding the alveoli.
At the same time,carbon dioxide in the blood capillaries diffuses into the
Alveoli.
7. Oxygen combines with haemoglobin in the red blood cells to form
oxyhaemoglobin.
8. When the oxyhaemoglobin reaches the target body cells and becomes
haemoglobin again.
9. The aim of cell respiration is to obtain energy for the body.
10. Most living things carry out cell respiration using oxygen. However, some
living things do not use oxygen for respiration e.g. yeast and some
bacteria.
11. Some substances are very harmful to the respiratory system.