Generation of Respiratory Rhythm Flashcards

1
Q

effect on breathing of removal of cortex and upper pons

A

slow gasping breaths

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2
Q

effect on breathing of removal of pons

A

return to rhythmic breathing

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3
Q

effect on breathing of removal of medulla

A

breathing stops

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4
Q

what aspect of breathing does the cortex control

A

voluntary breathing

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5
Q

what aspect of breathing do the pons, medulla and spinal cord control

A

automatic breathing

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6
Q

what groups in the brainstem help control automatic breathing

A

pontine respiratory group (PRG)
ventral respiratory group (VRG)
dorsal respiratory group (DRG)

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7
Q

what are medullary neurones

A

VRG, DRG
expiratory neurones

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8
Q

what do expiratory neurones do

A

inhibit inspiratory neurones

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9
Q

what do inspiratory neurones do

A

activate expiratory neurones
causes contraction of inspiratory muscles

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10
Q

what is the effect of inspiratory neurones during large inspirations

A

large activation of expiratory neurones

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11
Q

what is the effect of expiratory neurones during large inspirations

A

causes contraction of expiratory muscles

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12
Q

things that change the basic breathing pattern

A

inhaled noxious substances
speech/volition
sleep
exercise

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13
Q

feedback inputs - lung receptors

A

slowly adapting receptors
rapidly adapting receptors
c-fibre endings
all have afferent nerve fibres carried in vagus nerve

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14
Q

feedback inputs - chemoreceptors

A

central chemoreceptors
peripheral chemoreceptors

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15
Q

effect of vagal nerves cut on breathing

A

slow, deep breaths

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16
Q

effect of vagal nerves stimulated on breathing

A

shallow, rapid breaths

17
Q

slowly adapting lung receptors

A

aka stretch receptors
mechanoreceptors situated close to airway smooth muscle
stimulated by stretching of airway walls during inspiration
help initiate expiration and prevent overinflation of lungs
initiate hering-breuer inflation reflex (prolonged inspiration produced prolonged expiration)
afferent fibres = myelinated

18
Q

rapidly adapting lung receptors

A

aka irritant receptors
located in airway epithelium
primarily a mechanoreceptor so respond to rapid lung inflation
respond to chemicals (e.g. histamine), smoke, dust
RARs in trachea and large bronchi initiate cough, mucus production, bronchoconstriction
afferent fibres = myelinated

19
Q

c-fibre endings

A

bronchial c-fibre endings in airway epithelium
unmyelinated nerve fibres
stimulated by increased interstitial fluid (oedema) and various inflammatory mediators (histamine, prostaglandins, bradykinins)
pulmonary c-fibre endings close to pulmonary capillaries - aka juxtapulmonary capillary receptors, J-receptors

20
Q

peripheral chemoreceptors response to arterial o2 and co2

A

fast response to:
arterial pO2
arterial pCO2
arterial H+

21
Q

central chemoreceptors response to arterial o2 and co2

A

slow response to arterial pCO2

22
Q

oxygen terminology

A

above normal = hyperoxia
normal = normoxia
below normal = hypoxia or hypoxaemia in blood

23
Q

carbon dioxide terminology

A

above normal = hypercapnia
normal = normocapnia
below normal = hypocapnia

24
Q

what happens when pCO2 crosses the blood-brain barrier

A

equilibrium: pCO2 + H2O <-> H+ + HCO3-
H+ detected by central chemoreceptors on surface of medulla which stimulate medullary rhythm generator

25
Q

what does hypoxia and co2 buildup result in

A

chronic hypercapnia

26
Q

what does chronic hypercapnia result in

A

loss of sensitivity of central chemoreceptors

27
Q

drugs and respiration - depressants

A

anaesthetics - almost all
analgesics - opioids
sedatives (anti-anxiolytics, sleeping tablets) - benzodiazapines (diazepam, temazepam, etc)

28
Q

clinical examples of respiratory depressants

A

recreational drug overdose, procedural sedation

29
Q

drugs and respiration - stimulants

A

primary action - doxapram
secondary action - beta-2-agonists (bronchodilators)

30
Q

upper airway muscle activity - phasic

A

contraction of upper airway muscles
opening of upper airway
facilitates inward airflow
similar to activity in diaphragm/external intercostals which generate inspiration

31
Q

upper airway muscle activity - tonic

A

continuous background activity
tends to maintain patent airway
varies with state of alertness
similar to activity in skeletal muscles which maintain posture

32
Q

obstructive sleep apnoea

A

common
fragments sleep causing daytime sleepiness
important cause of traffic accidents
risk factors - obesity, alcohol, nasal obstruction, anatomical anomalies