The
breathing centre located near the rear of the brain regulates our breathing. The
breathing centre (also called the master centre of the body) uses special
chemoreceptors to measure CO2 concentrations in the brain and arterial blood.
The breathing of healthy people during typical daily activities (rest, work, light and moderate exercise, sleeping, etc.) is mainly regulated by the pre-set (or their usual) CO2 concentrations.
For
example, when a healthy person takes several deep and fast breaths, CO2 in the
lungs and blood falls. The breathing centre detects this drop and stops the work
of the respiratory muscles. The person naturally holds their breath until the CO2
level reaches the initially pre-set value. Conversely, breath holding
accumulates more CO2. The breathing centre senses this increase and intensifies
breathing. This over-breathing is going to continue until extra CO2 is removed
and the pre-set value is reached again.
We breathe more heavily during physical exercise, when our bodies produce more CO2. However, the rate of CO2 production matches the rate of CO2 removal in such a fashion that CO2 and O2 values in the arterial blood changes during exercise only slightly.
The breathing of sick people is regulated, in addition to CO2, by current blood O2 concentrations. The urge for oxygen gets stronger with the advance of many diseases. How and why this happens are some of the least known areas in medicine and physiology.
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* Illustrations by Victor Lunn-Rockliffe
© 2008 Artour Rakhimov (If you copy the content of these pages for educational purposes, please, indicate the site address and author's name).
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