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Y1 - Respiratory > Physiology 4: Control of Respiration (L6) > Flashcards

Physiology 4: Control of Respiration (L6) Flashcards

1
Q

Name the 2 divisions of respiratory control

A
  • Neural Control

- Chemical Control

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2
Q

Where in the brain is the respiratory centre located

A

The Pons and Medulla Oblongata

In the brainstem

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3
Q

Name the 3 respiratory groups in the brain

Give their locations

A
  • Pontine respiratory group (Pons)
  • Ventral respiratory group (Medulla oblongata)
  • Dorsal respiratory group (Medulla oblongata)
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4
Q

Name the 2 parts of the pontine respiratory group

Give their locations

A
  • Pneumotaxic centre (Superior)

- Apneustic centre (Inferior)

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5
Q

What is the general function of the medullary respiratory centres?

A

To generate rhythm

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6
Q

Describe the Pre-Botzinger complex

A
  • Part of the ventral respiratory group
  • Generates breathing rhythm
  • Exhibits pacemaker activity (Rhythmic firing)
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7
Q

Describe the dorsal respiratory group

A
  • Stimulated by the Pre-Bötzinger complex
  • A medullary respiratory centre
  • Fires in bursts to cause contractions of inspiratory muscles
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8
Q

Describe the neural process that leads to inspiration and then expiration

A
  • Pre-Bötzinger complex
    generates rhythm
  • Excites dorsal respiratory group neurons
  • Dorsal respiratory group neurons fire as a burst
  • Causes the contraction of inspiratory muscles and the pneumotaxic centre to fire
  • Pneumotaxic centre inhibits inspiration
  • Dorsal firing stops, inspiratory muscles relax
  • Passive expiration
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9
Q

What is the consequence of increased dorsal respiratory group neuron firing?

A
  • Excites the ventral respiratory group

- Causing active expiration

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10
Q

Describe the ventral respiratory group

A
  • A medullary respiratory centre
  • Excited by the increased firing of dorsal respiratory group neurons
  • Activate active expiratory muscles
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11
Q

Do ventral respiratory group neurons activate active expiratory muscles in normal breathing?

A

No

Only during active expiration

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12
Q

Describe the pneumotaxic centre

A
  • Located in the pontine respiratory group
  • Stimulated by dorsal respiratory group neurons
  • Its stimulation terminates inspiration
  • Prevents apneusis (long inspirations with short expirations)
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13
Q

When the pneumotaxic centre is not functioning what condition is observed

A

Apneusis

Prolonged inspiration, brief expiration

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14
Q

Describe the apneustic centre

A
  • Located in the pontine respiratory group
  • It fires to excite the ventral respiratory group (prolonging inspiration)
  • (Apneustic centre wants apneusis)
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15
Q

What is the general function of the pontine respiratory centres?

A

To modify the rhythm generated by the medulla

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16
Q

Describe the neural process that leads to active expiration

A
  • Pre-Bötzinger complex
    generates rhythm
  • Excites dorsal respiratory group neurons
  • Dorsal respiratory group neurons fire more than normal
  • Causes the contraction of inspiratory muscles more than normal (and the pneumotaxic centre to fire)
  • Pneumotaxic centre inhibits inspiration
  • Increased dorsal group firing activates the ventral resp group, activates active expiratory muscles
  • Dorsal firing stops –> inspiratory muscles relax
  • Active expiration
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17
Q

The respiratory centres are influenced by stimuli received from different places.

List these places

A
  • Higher brain centres (cerebral cortex, hypothalamus)
  • Pulmonary stretch receptors
  • J receptors
  • Temperature
  • Adrenaline
  • Joint receptors
  • Baroreceptors
  • Central chemoreceptors
  • Peripheral chemoreceptors
18
Q

Describe the function of pulmonary stretch receptors in the lungs in influencing respiratory centres

A
  • In the walls of bronchi and bronchioles
  • Activated by large inspiration
  • Activation inhibits inspiration
  • The Hering-Breuer inflation reflex prevents hyperinflation
19
Q

Describe the function of J receptors in the lungs in influencing respiratory centres

A
  • Juxtapulmonary (J) receptors

Stimulated by:

  • Pulmonary capillary congestion
  • Pulmonary oedema
  • Pulmonary emboli
20
Q

Describe the function of joint receptors in the lungs in influencing respiratory centres

A
  • Stimulated by joint movement (usually in exercise)

NB: (joint receptors ARE NOT J-receptors)

21
Q

Describe the function of baroreceptors in the lungs in influencing respiratory centres

A

Decreased bp causes an increased respiratory rate

22
Q

Describe the Hering-Breuer inflation reflex

A
  • Pulmonary stretch receptors detect excessive inspiration
  • Signal to respiratory centres
  • Inhibit inspiration
23
Q

List factors that may increase ventilation during exercise

A
  • Joint receptor stimulation
  • Adrenaline release
  • Cerebral cortex
  • Increase temp (hypothalamus)
  • Accumulation of carbon dioxide and hydrogen ions
24
Q

Describe how a cough is stimulated

A
  • Airway irritation or chemical detection
  • Nerve impulse to cough centre in the medulla
  • Stimulates a cough
25
Q

Is chemical control of respiration a negative or positive feedback control system?

A

-ve feedback control system

26
Q

Name the 2 types of chemoreceptors

A
  • Peripheral Chemoreceptors

- Central Chemoreceptors

27
Q

Describe peripheral chemoreceptors

A
  • Found in the carotid bodies and aortic bodies
  • Sense the blood gas tensions of oxygen and carbon dioxide
  • Senses the [hydrogen ions] in the blood
28
Q

What are the carotid bodies and aortic bodies?

A

Carotid:
- Regions of peripheral chemoreceptors in the carotid arteries

Aortic:
- Regions of peripheral chemoreceptors in the aora

29
Q

Describe central chemoreceptors

A
  • Located near the medullary surface

- Responds to [hydrogen ions] in the cerebrospinal fluid (CSF)

30
Q

Define blood gas tension

A

The partial pressure of a gas dissolved in the blood

31
Q

Give the acronym for the partial pressure of a gas in:

  • Arteries, veins, capillaries, alveoli
A

Artery - a
Alveoli - A
Vein - v
Capillary -c

(include this as subscript between the “P” and The formula of the gas)

32
Q

The cerebrospinal fluid is separated from blood by what?

A
  • The blood-brain barrier
33
Q

Describe the permeability of the blood-brain barrier to:

  • Hydrogen ions
  • Bicarbonate ions
  • CO2
A

Relatively impermeable:

  • Hydrogen ions
  • Bicarbonate ions

Easily Diffuses:

  • CO2
34
Q

Describe the buffering ability of cerebrospinal fluid

A

Less than blood

As it has less protein

35
Q

Describe the effect of arterial hypercapnia on:

  • Peripheral chemoreceptors
  • Central chemoreceptors
A

Peripheral Chemoreceptors:

  • Weak Stimulation

Central Chemoreceptors:

  • Poor buffering in the CSF allows the readily diffused CO2 to generate hydrogen ions
  • These H ions dominantly stimulate (dominant control of ventilation)
36
Q

Describe the effect of arterial hypoxia on:

  • Peripheral chemoreceptors
  • Central chemoreceptors
A

Peripheral Chemoreceptors:

  • Stimulated if PO2 < 8kPa
  • Called the hypoxic drive of respiration

Central Chemoreceptors:

  • Severe hypoxia depresses the respiratory centres
37
Q

Describe when the hypoxic drive of respiration occurs

A
  • Not during normal respiration
  • If PO2 falls below 8kPa
  • Important if chronic CO2 retention (COPD), or at high altitudes
38
Q

Define the hypoxic drive of respiration

A

The stimulation of peripheral chemoreceptors by a low PO2

39
Q

What are the acute responses to hypoxia?

A
  • Hyperventilation

- Increases cardiac output

40
Q

What are the chronic responses to hypoxia?

Describe the purpose of these changes

A
  • Red blood cell production (better oxygen carrying capacity)
  • Increased 2,3-bisphosphoglycerate in RBCs (oxygen offloaded more readily at tissue)
  • More capillaries (better difusion)
  • More mitochondria (more efficient oxygen use)
  • Kidneys conserve acid (arterial pH decrease)
41
Q

Describe the effect of arterial H ions on:

  • Peripheral chemoreceptors
  • Central chemoreceptors
A

Peripheral Chemoreceptors:

  • Stimulation (important in acid-base balance)

Central Chemoreceptors:

  • No effect (H ions can’t cross the blood brain barrier)

Y1 - Respiratory (7 decks)

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