Control of breathing-asleep Flashcards
what is apnoea?
The cessation of breathing
What is apnoeic threshold?
The level of blood gas you need to maintain breathing
what is the difference between sleep and other forms such as coma?
Sleep is reversible
How do we measure sleep?
Using a Electroencephalogram (EEG)
what stage of sleep makes you feel better?
Stage 4 which is deep sleep, this is what makes you feel better and restored
what stage do you dream and describe how this stage changes as you go through the night>
In your REM sleep. Deep sleep decreases and the amount of REM sleep increases.
The body becomes functionally paralysed during REM sleep. What two muscles are spared? What implications does this have for breathing?
Eye muscles
Diaphragm
The accessory muscles (e.g. intercostals) are no longer active so it becomes more difficult to breathe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.
what are the 2 ways in which breathing during sleep is controlled?
Brainstem: reflex/automatic
Cortex: Voluntary/ behavioural
how is the breathing when your sleeping controlled?
There is NO corticol control when you’re sleeping. Most of the time there is some input from the cortex unless you’re in deep sleep.
Name a complex in the medulla that is involved in regulating the respiratory rhythm.
Pre-Botzinger Complex.
It is a cluster of respiratory nuclei found on the rostral-ventral-lateral medullary surface.
What models are used to determine certain neuronal control pathways?
Lesion Deficit Models.
This is using patients who have had bleeds in different parts of the brain
why does blood gases change ?
Because there is less input from the respiratory centres and so you have less output to the respiratory muscles. As a result, blood gases change when you go to sleep.
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 Breathing becomes shallower. Little change in oxygen saturation.
What plays the biggest role in the control of breathing when awake?
PCO2 levels
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. This allows CO2 levels to rise when we sleep.
What is the apnoeic threshold?
The minimum PCO2 required to trigger breathing
Suggest why becoming less sensitive to CO2 might be beneficial?
It gives us more blood gas range before we wake ourselves up
What happens if you prevent the carbon dioxide levels from exceeding the apnoeic threshold?
You stop breathing