The process of gas exchange in the alveoli and cells of the body:

1. The high oxygen content in the alveoli causes the process of oxygen diffusion into the blood capillaries to occur

2. In the blood capillaries, oxygen combines with hemoglobin to form oxyhaemoglobin

3. The oxyhaemoglobin is transported using red blood cells to all cells of the body and oxygen is released

4. In the cells of the body, the process of oxidation (cellular respiration) takes place to produce energy and carbon dioxide

5. The carbon dioxide permeates from the cells into the capillary tissue and is subsequently transported to the lungs for elimination

The adaptation of alveolar structure to maximize gas exchange:

• A large surface area for gas exchange in the alveoli can increase the oxygen content

• The surface of the alveoli is moist so that gas easily permeates out and into the alveoli

• The alveoli are thin-walled as thick as one cell to facilitate gas prescription

• The alveoli are surrounded by a network of blood capillaries to facilitate rapid gas transport