Respiratory Physiology: Ventilation Control Flashcards

1
Q

Ventilation control require stimulation of what muscles during inspiration

A

Skeletal

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2
Q

Where does ventilation control occur via

A

Phrenic (to diaphragm) and intercostal nerves (to external intercostal muscles)

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3
Q

Where does ventilation control reside

A

ill-defined centres located in the pons and medulla

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4
Q

What is PRG and what does it modulate

A

Pontine respiratory group located in the Pons and it modulates DRG and VRG

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5
Q

What does VRG and DRG stand for

A

Ventral Respiratory Group and Dorsal Respiratory Group

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6
Q

What does VRG control

A

Expiration (tongue, pharynx and larynx)

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7
Q

What does DRG control

A

Inspiration (via phrenic and intercostal muscles)

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8
Q

What are the 4 basis’ of rhythm of respiration

A
  1. Emotion (via limbic system)
  2. Voluntary over-ride (via higher centres in the brain)
  3. Mechano-sensory input from the thorax (stretch reflex to prevent over-expansion)
  4. Chemoreceptors which detect chemical composition of the blood (PCO2, PO2 and PH)
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9
Q

Which of the 4 basis of rhythm is the most significant

A

Chemoreceptors

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10
Q

Where is the central chemoreceptor located

A

Medulla

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11
Q

What is the stimuli which activates the central chemoreceptor

A

Responds directly to H+ (directly reflects PCO2)

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12
Q

Where do these changes occur and how does this effect the ventilatory drive

A

Occurs in the CSF. CO2 combines with H20 to form carbonic acid and H+ and is the primary ventilatory drive

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13
Q

Hypercapnea

A

Raised PCO2 in CSF

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14
Q

Does the central chemoreceptor respond directly to changes in the plasma (Y/N)

A

N

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15
Q

What crosses the blood brain barrier when PCO2 in arterial blood increases?

A

H+

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16
Q

Where are the peripheral Chemoreceptors located

A

Carotid and Aortic bodies

17
Q

What is the stimuli which activates the peripheral chemoreceptor

A

Responds primarily to plasma [H+} and PO2 and is the secondary ventilation drive

18
Q

What happens if plasma pH falls [H+ increases]

A

Acidosis, ventilation is stimulated

19
Q

What happens if plasma pH increases [H+ falls]

A

Alkalosis, vomiting and ventilation will be inhibited

20
Q

Common drugs affecting respiratory centres

A

Barbiturates and Opioids
Gaseous anaesthetic agents
Nitrous Oxide

21
Q

How do Barbiturates and Opioids effect Respiratory Centres

A

They depress respiratory centres that can lead to respiratory failure

22
Q

How do gaseous anaesthetic agents effect Respiratory Centres

A

Increase RR but decrease Tidal Volume so decrease Alveolar Ventilation

23
Q

How does nitrous oxide effect the respiratory centres

A

blunts peripheral chemoreceptors response to falling arterial oxygen