Initation and mechanics of breathing. Flashcards
Where is the repiratory centre located?
In the brainstem
Which groups of neurones send impulses to the repiratory muscles?
1) Medullary rhythmicity- Inspiratory and Expiratory groups (medulla oblongata)
2) Pneumotaxic centre- Helps smooth the breathing cycle
3) Apneustic centre- Modulates aspects of the breathing cycle (think gasping).
Where is automatic breathing initated?
In the dorsal and ventral respiratory groups in the medulla oblongata.
What kind of neurones are found in the DRG?
Mainly inspiratory neurones.
When is the DRG active?
The DRG is mainly active during inspiration.
What does the DRG do?
The DRG drives the inspratory muscles.
The DRG has input from which nerves? Where do they terminate? What do they do?
The DRG has input from CN 9 and 10. They terminate in the nucleus tractus solitarius and they send sensory impulses from the lungs, airways, chemoreceptors and joint proprioceptors. This input modifies the respiratory pattern.
What kinds of neurones are found in the VRG?
The VRG contains both inspiratory and expiratory neurones.
What does the VRG do?
The VRG drives expiratory accessory muscles. It sends expiratory impulses to the abdominal muscles/ internal intercostals from neurones in the caudal area.
Is the VRG active during quiet breathing?
The VRG is SILENT during quiet breathing.
Does the VRG ever send inspiritory impulses?
Where to?
Yes. The VRG sends inspiritory impulses to the laryngeal and pharyngeal muscles from neurones in the nucleus ambiguus. It also sends impulses to the diaphragm and external intercostals from neurones located in the rostral area of the nucleus retroambigualis.
Which brainstem transection study resulted in the discovery of areas in the CNS that defined breathing rhythm?
A study carried out by Thomas Lumsden in 1923 using anaesthetized cats found that there are 3 discrete CNS centres that initiate ventilation.
**Think, normal breathing=normal brainstem.
Erratic patterns= cut between pons and medulla
No ventilation= spinal cord is severed **
