There are three phases of respiration:


Ventilation is the process by which oxygenated air passes through the respiratory tract during inspiration.


Perfusion is when blood from the pulmonary circulation is sufficient at the alveolar-capillary bed to conduct diffusion. In order for perfusion to occur, the alveolar pressure must be matched by adequate ventilation. The presence of mucosal edema, secretions and bronchospasm increase resistance to the airflow, which results in decreased ventilation. Decreased ventilation causes a decrease in diffusion.


Diffusion is the process where oxygen moves into the capillary bed and carbon dioxide leaves the capillary bed.

Coping with Asthma

Coping with Asthma

If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.

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