Neurological Control of Breathin

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The neurons of the VRG do not participate in quiet inspiration or expiration.

Text Box: The neurons of the VRG do not participate in quiet inspiration or expiration. Neurological Control of Breathing - Quiet Inspiration

When neurons of the DRG are not firing, the diaphragm and external intercostals relax and passive expiration occurs

Text Box: When neurons of the DRG are not firing, the diaphragm and external intercostals relax and passive expiration occurs

Inspiration

Increased intrathoracic volume
Decreased intrathoracic pressure

Text Box: Increased intrathoracic volume
Decreased intrathoracic pressure

The intercostal nerves for contraction of the external intercostal muscles

Text Box: The intercostal nerves for contraction of the external intercostal muscles

The phrenic nerves for contraction of the diaphragm

Text Box: The phrenic nerves for contraction of the diaphragm

Messages are carried down the spinal cord to:

Text Box: Messages are carried down the spinal cord to:

Neurons of the DRG spontaneously and rhythmically depolarize

Text Box: Neurons of the DRG spontaneously and rhythmically depolarize

Ventral Respiratory Group
(inspiratory center)

Text Box: Ventral Respiratory Group
(inspiratory center)

Dorsal Respiratory Group (DRG)

Text Box: Dorsal Respiratory Group (DRG)

Respiratory Rhythmicity Center in Medulla Oblongata

Text Box: Respiratory Rhythmicity Center in Medulla Oblongata

Dorsal Respiratory Group (DRG)

Text Box: Dorsal Respiratory Group (DRG)

Messages are carried down the spinal cord to:

Text Box: Messages are carried down the spinal cord to:

Messages are carried down the spinal cord to the secondary muscles of inspiration, namely, the pectoralis major and minor, the scalenes group and the sternocleidomastoids

Text Box: Messages are carried down the spinal cord to the secondary muscles of inspiration, namely, the pectoralis major and minor, the scalenes group and the sternocleidomastoids

The phrenic nerves for contraction of the diaphragm

Text Box: The phrenic nerves for contraction of the diaphragm

The intercostal nerves for contraction of the external intercostal muscles

Text Box: The intercostal nerves for contraction of the external intercostal muscles

Respiratory Rhythmicity Center in Medulla Oblongata

Text Box: Respiratory Rhythmicity Center in Medulla Oblongata

Forced Inspiration

Text Box: Forced Inspiration

Neurological Control of Breathing - Forced Inspiration

Ventral Respiratory Group (VRG)

Text Box: Ventral Respiratory Group (VRG)

Ventral Respiratory Group
(expiratory center)

Text Box: Ventral Respiratory Group
(expiratory center)

Forced expiration

Text Box: Forced expiration
Neurological Control of Breathing - Forced Expiration

Role of the Pons in Breathing

The pons contains two centers which control the transition from inspiration to expiration.

         1..The Apneustic center stimulates the inspiratory centers in the DRG and VRG for quiet
         and forced inspiration, respectively. At the same time, the apneustic center inhibits
         expiration.

          2. The Pneumotaxic center inhibits the apneustic center promoting a passive or forced
          expiration. As a result, the pneumotaxic center shortens inspiration and increases the rate
          of ventilation.

After a brief delay, the VRG stimulates contraction of expiratory muscles: the internal intercostals, and the abdominal muscles. At the same time, the inspiratory center of the VRG is inhibited.

Text Box: After a brief delay, the VRG stimulates contraction of expiratory muscles: the internal intercostals, and the abdominal muscles. At the same time, the inspiratory center of the VRG is inhibited.

Ceases to stimulate the external intercostals and diaphragm. They relax as before (passive component).

Text Box: Ceases to stimulate the external intercostals and diaphragm. They relax as before (passive component).