Published by Australian Academy of Science
Activity 4 | The rise and rise of asthma

How an asthma attack causes breathing difficulties

During an asthma attack, the smooth muscle surrounding airways leading to the airsacs of the lungs tighten or spasm.

• Explain why this closes off the smaller airways and causes breathing difficulties.

Teachers notes

The large airways to the lungs are supported by cartilage. However, the smallest airways (bronchioles) which lead to the air sacs (alveoli) are supported only by smooth muscle. When these muscles tighten or spasm, this makes the opening of the airways much narrower than usual so it is hard to move air in and out of the air sacs. In addition to the effect of the muscles tightening, the thin linings inside the airways swell and thick mucous plugs the airways. The symptoms experienced by an asthma sufferer are: breathlessness, wheezing, chest tightness and coughing.