Regulation of Breathing

 

 

Inspiration and Expiration movements are produced by the contraction of the inspiratory and expiratory muscles. These muscles are striated muscles and thus require nervous stimulation for contraction. These stimuli are transported through two descending tracts from the respiratory control centres (involuntary breathing) and from the cerebral cortex (voluntary breathing)

 

Brain Stem Respiratory Centres

Three areas within the Pons (two centres) and the medulla oblongata (one centre) control autonomic breathing.

Rhythmicity Centre

1

Situated in the Medulla oblongata

 

2

I neurons stimulate spinal motor neurons that innervate the respiratory muscles producing Inspiration

 

3

E neurons inhibit the I neurons and thus produce expiration by relaxation of the respiratory muscles

 

4

I and E neuronal activity varies in a reciprocal way so that a rhythmic pattern is obtained
     

Apneustic Centre

1

Situated in the Pons

 

2

Stimulate the I neurons in the Medulla Oblongata

 

3

Result in Inspiration

 

4

Provides a constant stimulus for inspiration

Pneumotaxic Centre

1

Situated in the Pons

 

2

Seems to antagonise the apneustic centre

 

3

Inhibits inspiration