Respiratory Center Simplified

Mnemonic: Boat starts and PRASaD DIVEs

1. pre-Botzinger complex Starts respiratory rhythm (pacemaker): Boat Starts

• Location: Between nucleus ambiguus and lateral reticular nucleus (upper medulla)

2. Pneumotaxic center Represses Apneustic center: PR-A

• Location: Upper pons (Nucleus parabrachialis and Kolliker-fuse nucleus)

3. Apneustic center Stimulates DRG: A-SaD

• Location: Lower pons

4. Dorsal respiratory group (DRG) for Inspiration (tidal): DI

• Location: Dorsal medulla (Nucleus Tractus Solitarius)

5. Ventral respiratory group (VRG) for Expiration (forced): VE

• Location: Ventrolateral medulla (Nucleus ambiguus and Nucelus retro-ambiguus)

In summary:

1. Rhythmic cycle of breathing originates in medulla (pre-botzinger complex).
2. Voluntary respiration is controlled by cerebral cortex. Limbic system and hypothalamus alter pattern of breathing in emotional stress such as fear and rage.
3. Involuntary respiration is controlled by upper brainstem.
4. DRG (NTS) is Inspiratory center (receives CN 9 and 10 afferents from peripheral chemoreceptors, airways and lungs)
5. VRG (Nucleus ambiguus and retro-ambiguus) is Expiratory center (however, it has both inspiratory and expiratory neurons)
6. Apneustic center stimulates DRG (inspiratory center) and causes inspiration (Apneusis = Prolonged inspiratory gasps).
7. Pneumotaxic center (Nucleus parabrachialis and Kolliker fuse nucleus) and CN 10 inhibit Apneustic center to limit inspiration (volume) and increase the rate of respiration. Under normal conditions, after 2 seconds, apneustic center is inhibited by pneumotaxic center.

Effect of lesion/transection:

From superior to inferior: