Control of Ventilation Flashcards
Where in the body is ventilation controlled?
- Respiratory centre
- Brain stem: pons and medulla
Is arterial blood PO2 and PCO2 ever altered?
- No (rarely)
- Since nervous system adjusts the rate of alveolar ventilation
What are respiratory sensors?
- Chemoreceptors
- Lung receptors
- Other receptors
What are respiratory effectors?
- Respiratory muscles
What does the medullary respiratory group consist of?
- Dorsal respiratory group
- Ventral respiratory group
What is the function of the dorsal respiratory group?
- Inspiratory neurons
- Fire signals inducing muscle contraction → inspiration
external intercostals + diaphgram
What is the function of the ventral respiratory group?
- Both inspiratory and expiratory neurons
- Remain inactive during quiet breathing
- Used when demand of ventilation is increased (active expiration)
What kind of breathing rhythms does the medulla generate?
pacemaker like activity
- normal breathing (fast, low amplitude)
- sighs (slow, large)
What does the Pons respiratory group consist of?
- Pneumotaxic center
- Apneustic center
What do the pneumotaxic group do?
- Inhibits inspiratory neurons
- sends signal to DRG
- prevents over-inflation of lungs
What does the apneustic group do?
- Prevents inspiratory neurons from being switched off
- Stimulates DRG and VRG
What is the neuronal oscillatory circuit?
- Inspiratory circuit fires for 2 seconds
- Inspiratory circuit dormant for 3 seconds (expiration occurs)
expiratory circuit activated during exercise
What are strong and weak breathing impulses?
- Strong: 0.5s inspiration
- Weak 5-7s inspiration
What is the Hering-Breur Reflex?
- Stretch receptors in lung tissue, bronchi, bronchioles
- transmit inhibitory signals via vagus nerve (X) to inspiratory area; prevents over inflation go lungs
What does an impaired respiratory circuit cause?
- Hypoventilation + hypoxemia