Control of Ventilation Flashcards

1
Q

What muscles does ventilation require use of?

A

Skeletal muscles of inspiration (external intercostals and diaphragm)

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2
Q

What is the nerve that innervates the diaphragm?

A

Phrenic

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3
Q

What nerves innervate the intercostal muscles during inspiration?

A

Intercostal nerves

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4
Q

Where are the respiratory centres?

A
  • Pons - Medulla
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5
Q

If you severe the spinal chord above C3-5 what happens?

A

Breathing stops

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6
Q

What 2 conditions do the respiratory centres work in?

A
  • Set an automatic breathing rhythm - Adjust breathing rhythm in response to stimulus
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7
Q

How do the respiratory centres keep an automatic breathing rhythm?

A
  • Constant regular AP’s in the dorsal respiratory group
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8
Q

What 4 things regulate the respiratory system (think about times when your breathing rate increases?)

A
  • Emotion (limbic system) - Voluntary override - Mechanosensory (exercise, stretch reflex) - Chemical composition (PCO2 etc.)
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9
Q

What receptors detect a change in the chemical composition of the blood?

A

Chemoreceptors

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10
Q

What is the VRG?

A

Ventral Respiratory Group

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11
Q

What is the DRG?

A

Dorsal Respiratory Group

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12
Q

What does the VRG control?

A
  • Tongue - Pharynx - Larynx - Expiratory muscles
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13
Q

What does the DRG control?

A
  • Inspiratory muscles
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14
Q

Where are central chemoreceptors found?

A

Medulla

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15
Q

What do central chemoreceptors respond to and how do they respond?

A
  • H+ in the CSF - Primary ventilatory drive (increase in ventilation
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16
Q

Where are peripheral chemoreceptors?

A
  • Carotid - Aorta
17
Q

What do peripheral chemoreceptors respond to?

A
  • Plasma H+ - Plasma PCO2 and PO2 (not as much)
18
Q

What is the reaction of peripheral chemoreceptors?

A

Secondary ventilatory drive

19
Q

What does H+ directly show if it is raised?

A

PCO2 is also high

20
Q

What is raised PCO2 called?

A

Hypercapnea

21
Q

How are central chemoreceptors able to detect PCO2?

A
  • CO2 can cross blood brain barrier - Dissociates into H+ and HCO3 - H+ detected by chemoreceptor
22
Q

When do peripheral chemoreceptors cause a reflex stimulation of ventilation?

A
  • When blood PO2 is very low - A rise in H+ conc
23
Q

If acidosis occurs, what will happen to ventilation through chemoreceptors?

A

Ventilation increases

24
Q

If alkalosis occurs, what will happen to ventilation?

A

Will be reduced

25
Where do all pathways that have a reflex control of ventilation converge?
Medulla Oblongata
26
How are the signals from the carotid and aortic chemoreceptors transferred to the medulla?
Afferent sensory neurons
27
What neurones are activated by the medulla to cause inspiration and expiration?
Somatic motor neurons
28
What structures are innervated by somatic inspiratory neurones?
- Diaphragm - External intercostals - Scalene and sternocleidomastoid
29
What structures are innervated by the somatic expiratory nerves?
- Internal intercostals - Abdominal muscles
30
STUDY THIS DIAGRAM
31
What other part of the brain has descending neural pathways that allow voluntary breathing control?
Central Cortex
32
What drugs depress the respiratory centre?
- Barbiturates - Opioids
33
What happens to respiration after swallowing?
- Initial breath out to move particles from airway at epiglottis - Ventilation is inhibited