Flashcards in Control of Breathing (asleep) Deck (19):
The body becomes functionally paralysed during REM sleep. What two muscles are spared? What implications does this have for breathing?
The accessory muscles (e.g. intercostals) are no longer active so it becomes more difficult to breathe
What centre controls breathing and where is it located?
Respiratory Centre - medulla
How does the control of breathing change when asleep compared to when awake?
When asleep, cortical and emotional control of breathing is inactive. It is solely regulated by the respiratory centre.
Name a complex in the medulla that is involved in regulating the respiratory rhythm.
What models are used to determine certain neuronal control pathways?
Lesion Deficit Models
How do minute ventilation and tidal volume change when asleep?
Minute Ventilation = DECREASES (10% reduction in minute ventilation)
Tidal Volume = DECREASES
NOTE: frequency remains roughly the same
What plays the biggest role in the control of breathing when awake?
How does oxygen saturation change when asleep? Explain your answer.
Oxygen saturation remains the same - because you are at the flat part of the oxygen dissociation curve meaning that despite a decrease in PO2, oxygen saturation stays the same.
NOTE: During REM sleep, you PO2 and SO2 drop slightly
Why might this be different for someone with lung disease?
People with lung disease live on the steeper part of the ODC so a reduction in PO2 during sleep can cause a marked reduction in oxygen saturation.
How do carbon dioxide levels change when you go to sleep?
Carbon dioxide levels rise when you go to sleep.
How does the level of carbon dioxide required to trigger breathing change when you go to sleep?
INCREASES - a higher PCO2 is required to trigger breathing
How does sensitivity to carbon dioxide change when you go to sleep?
Sensitivity to carbon dioxide decreases when you go to sleep - there is a smaller change in minute ventilation per 1 kPa rise in PCO2
What is the apnoeic threshold?
The minimum PCO2 required to trigger breathing
What happens if you prevent the carbon dioxide levels from exceeding the apnoeic threshold?
You stop breathing
Describe the structure of the upper airways (pharynx).
It is a muscular collapsible tube with no cartilage rings holding it open.
Describe what causes obstructive sleep apnoea.
Relaxation of the muscular parts of the upper airways, negative intraluminal pressure and positive extraluminal pressure can lead to collapse of the airways.
Muscles involved: epiglottis, tongue, pharyngeal muscles (not totally sure about this - just some suggestions)
Describe the cycle that takes place in someone suffering from obstructive sleep apnoea.
Sleep --> decrease in upper airway muscle function --> apnoea --> arousal --> patent airway --> ventilation
All starts again
How does central sleep apnoea differ from obstructive sleep apnoea?
This is a chemosensitivity issue rather than a mechanical obstruction