The Human Brain : From Neurone to Nervous System


  1. Normal quiet breathing consists of active inspiration followed by passive expiration; when respiratory efforts are increased, active expiration also comes into play.

  2. Brainstem neurones that control breathing can be divided into groups that regulate these three phases of the breathing cycle.

  3. Neurones with a respiratory rhythm exist in a number of sites throughout the medulla. An important group of neurones that generate the respiratory rhythm can be found within a column known as the ventral respiratory column. Within this column one particular group of neurones, the pre-Bötzinger complex (preBötC), are essential for breathing, and are seen as the primary respiratory rhythm generator.

  4. The older literature described a pontine pneumotaxic centre that could modify the rhythm and depth of breathing: recently it has been possible to identify which pontine neurones are involved.

  5. Respiratory rhythm and tidal volume are increased when arterial pCO2 is elevated, a phenomenon that depends upon sensors known as the central chemoreceptors, which exist on the ventro-lateral surface of the medulla and are in close contact with the cerebrospinal fluid.

  6. Key Words: Respiratory rhythm; respiratory neurones; central chemoreceptors; pneumotaxic centre