RESPIRATION
· Pathway taken by air during inhalation:
Nostril ---> Nasal cavity--> Trachea--->Bronchus---->Bronchiole--->Alveolus
· Pathway taken by air during exhalation:
Alveolus
--->
Bronchiole
-->
Bronchus
--->
Trachea
---->
Nasal cavity
--->
Nostril
Transport of oxygen in human body
v Exchange of gases takes place in the alveoli by diffusion.
v Characteristics of alveoli that help exchange of gases to take place effectively:
| | Ø Has one-cell thick wall ( very thin) Ø Inside surface has thin film of moisture Ø Huge number of alveoli Ø Network of blood capillaries surround each alveoli |
TRANSPORTATION OF OXYGEN
- Oxygen dissolves in the moist lining of the alveolus
- Then, oxygen diffuses into the blood capillaries
- Blood inside the capillaries contains red blood cells that are rich with haemoglobin
- Oxygen combines with haemoglobin to form oxyhaemoglobin
- Oxyhaemoglobin is transported in the blood to heart and then pump to all parts of the body
- Oxyhaemoglobin breaks down, oxygen diffuses into the cells, at the same time carbon dioxide diffuses into the blood
EFFECTS OF OTHER AIR POLLUTANTS
| CHEMICAL SUBSTANCE | SOURCES | DAMAGING EFFECTS |
| Carbon monoxide | Car exhaust | Reduces amount of oxygen in the food |
| Sulphur dioxide | Industry, vehicles | Damages lung tissues |
| Hydrocarbons | Industry, vehicles | Cause cancer |
| Nitrogen oxide | Industry, vehicles | Interacts with hydrocarbons to form haze |
| Haze | Industry, vehicles, open burning | Causes breathing difficulties |
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