Regulation and disorders of breathing

You do not have to remember to breathe. A special group of neurons in the medulla, the respiratory rhythm centre, sets the rhythm of breathing and adjusts it to the body's needs.

In the pons, the pneumotaxic centre fine-tunes it: its signals shorten each breath in, which changes the breathing rate.

Right next to the rhythm centre is a chemosensitive area, highly sensitive to CO₂ and H⁺ (acidity). When these rise, as during exercise, it tells the rhythm centre to make you breathe faster and deeper, to get rid of them. Receptors on the aortic arch and the carotid artery also sense these changes and send signals. Surprisingly, oxygen plays only a very small role in controlling the breathing rhythm.

Some disorders of the respiratory system:

• Asthma: difficulty in breathing, with wheezing, because the bronchi and bronchioles become inflamed.
• Emphysema: a long-term disease in which the walls of the alveoli are damaged, so the surface for gas exchange shrinks. Cigarette smoking is one of its major causes.
• Occupational disorders: in industries involving grinding or stone-breaking, so much dust is produced that the body's defences cannot cope. Over time it causes inflammation and scarring (fibrosis) and serious lung damage. Workers in such places should wear protective masks.