Control of Ventilation Flashcards
Breathing depends on cyclical activation of what nerves?
Phrenic
Intercostals
The phrenic and intercostal nerves stimulate contraction of what muscles?
Inspiratory
The neural activity of rhythmic breathing is triggered by what neurones?
Medullary inspiratory neurones
Breathing is triggered by the medullary inspiratory neurones with
voluntary override
What muscle of inspiration does the phrenic nerve innervate?
The diaphragm
Ventilatory control resides within ill-defined centres located in the
pons and medulla
Is ventilatory control normally conscious or subconscious?
Subconscious
If the spinal cord was severed above the origin of the phrenic nerve, what would happen to breathing?
It would cease
At what vertebral level is the origin of the phrenic nerve?
C3-C5
What are the functions of respiratory systems
- to set an automatic rhythm of breathing
- to adjust this rhythm in response to stimuli
How do respiratory systems set an automatic rhythm of breathing?
Through co-ordinating the firing of smooth and repetitive bursts of action potentials in dorsal respiratory group (DRG)
What factors modulate the rhythm of respiratory centres?
- emotion
- voluntary override
- mechano-sensory input from the thorax (e.g. stretch reflex)
- chemical composition of the blood (PCO2, PO2 and pH, detected by chemoreceptors)
The rhythm of respiratory centres is modulated by emotional input via what system?
The limbic system
Input from higher brain centres changes the respiratory system rhythm via
voluntary override
Where are central chemoreceptors located?
Medulla
