Impact of exercise, asthma and smoking on gas exchange

In a nutshell

Exercise, asthma and smoking can all impact the gas exchange system and the way in which people breathe.

Exercise

During exercise, the muscles in the body require more energy to keep up. In order to get more energy, the muscles need a greater amount of oxygen for respiration. To get more oxygen into the lungs during exercise, the body increases the breathing rate and depth of breathing.

Over time, regular exercise can strengthen the muscles used in breathing - the diaphragm and intercostal muscles. This allows the chest cavity to expand further during inhalation, so more air can enter the lungs. Regular exercise can also make gas exchange more efficient by increasing the number of small blood vessels and alveoli in the lungs.

Asthma

Asthma is a common condition that affects the lungs. People with asthma have lungs (asthmatic) that are sensitive to certain things, including pet hair, dust and smoke. If an asthmatic breathes these things in, it can trigger an asthma attack.

1.	An asthmatic breathes in something they are sensitive to. Example Pet hair or pollen.
2.	The muscles surrounding their bronchioles contract, narrowing their airway.
3.	The lining of the airways becomes inflamed and mucus builds up in the airways. This makes it more difficult to breathe.
4.	A person having an asthma attack may have symptoms including wheezing, a tight chest and feeling short of breath.

Asthmatics are given inhalers which contain medicine that helps to open up the airways when they have symptoms of an asthma attack.

Smoking

The four main substances in cigarette smoke are carbon monoxide, tar, nicotine and particulates.

Tar is especially bad for people and can cause problems within the gas exchange system. Tar tends to cover the little hairs on the lining of the airways. The little hairs are called cilia and they help to clear the airways by removing extra mucus. Tar damages the cilia, which results in mucus sticking to the airways. This causes people to cough more and develop a smoker's cough.

Over time, the damage from smoking builds up and can lead to serious lung conditions like bronchitis and emphysema:

Bronchitis	A disease which causes inflammation in the bronchi lining.
Emphysema	A disease which destroys the alveoli in the lungs.

Both bronchitis and emphysema can make it difficult for people to breathe. Tar also contains substances which can cause cancer (carcinogens) of the lungs, throat and mouth.