Control of Breathing (asleep) Flashcards

1
Q

The body becomes functionally paralysed during REM sleep. What two muscles are spared? What implications does this have for breathing?

A

Eye muscles
Diaphragm
The accessory muscles (e.g. intercostals) are no longer active so it becomes more difficult to breathe

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2
Q

What centre controls breathing and where is it located?

A

Respiratory Centre - medulla

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3
Q

How does the control of breathing change when asleep compared to when awake?

A

When asleep, cortical and emotional control of breathing is inactive. It is solely regulated by the respiratory centre.

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4
Q

Name a complex in the medulla that is involved in regulating the respiratory rhythm.

A

Pre-Botzinger Complex

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5
Q

What models are used to determine certain neuronal control pathways?

A

Lesion Deficit Models

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6
Q

How do minute ventilation and tidal volume change when asleep?

A

Minute Ventilation = DECREASES (10% reduction in minute ventilation)
Tidal Volume = DECREASES
NOTE: frequency remains roughly the same

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7
Q

What plays the biggest role in the control of breathing when awake?

A

PCO2 levels

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8
Q

How does oxygen saturation change when asleep? Explain your answer.

A

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

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9
Q

Why might this be different for someone with lung disease?

A

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.

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10
Q

How do carbon dioxide levels change when you go to sleep?

A

Carbon dioxide levels rise when you go to sleep.

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11
Q

How does the level of carbon dioxide required to trigger breathing change when you go to sleep?

A

INCREASES - a higher PCO2 is required to trigger breathing

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12
Q

How does sensitivity to carbon dioxide change when you go to sleep?

A

Sensitivity to carbon dioxide decreases when you go to sleep - there is a smaller change in minute ventilation per 1 kPa rise in PCO2

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13
Q

What is the apnoeic threshold?

A

The minimum PCO2 required to trigger breathing

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14
Q

What happens if you prevent the carbon dioxide levels from exceeding the apnoeic threshold?

A

You stop breathing

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15
Q

Describe the structure of the upper airways (pharynx).

A

It is a muscular collapsible tube with no cartilage rings holding it open.

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16
Q

Describe what causes obstructive sleep apnoea.

A

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)

17
Q

Describe the cycle that takes place in someone suffering from obstructive sleep apnoea.

A

Sleep –> decrease in upper airway muscle function –> apnoea –> arousal –> patent airway –> ventilation
All starts again

18
Q

How does central sleep apnoea differ from obstructive sleep apnoea?

A

This is a chemosensitivity issue rather than a mechanical obstruction

19
Q

What are the implications of sleep apnoea on heart disease?

A

Patients with sleep apnoea have to generate massive pressures in their chest to allow them to breathe and this can exacerbate heart conditions.