Control of ventilation

[1] The most important function of breathing is the supplying of oxygen to the body and balancing of the carbon dioxide levels.

From the respiratory center, the muscles of respiration, in particular the diaphragm,[4] are activated to cause air to move in and out of the lungs.

), social communication causes speech, song and whistling, while entirely voluntary overrides are used to blow out candles, and breath holding (for instance, to swim underwater).

[7] The ventilatory pattern is also temporarily modified by complex reflexes such as sneezing, straining, burping, coughing and vomiting.

These levels are sensed by central chemoreceptors on the surface of the medulla oblongata for decreased pH (indirectly from the increase of carbon dioxide in cerebrospinal fluid), and the peripheral chemoreceptors in the arterial blood for oxygen and carbon dioxide.

The concentration of carbon dioxide (CO2) rises in the blood when the metabolic use of oxygen (O2), and the production of CO2 is increased during, for example, exercise.

Opioids and anesthetics tend to depress ventilation, by decreasing the normal response to raised carbon dioxide levels in the arterial blood.

Pregnancy tends to increase ventilation (lowering plasma carbon dioxide tension below normal values).