Initiation of Breathing Flashcards
Neurogenic initiation
What 2 things did Thomas Lumsden (1923) discover?
think:
- respiratory centres
- medulla and pons
- Discovered that 3 CNS respiratory centres were involved
- The medulla is of primary importance in breathing and Pons smooths out breathing
The respiratory centre
what type of groups send impulses to respiratory muscles
- bi-lateral groups
the respiratory centre
what do the Dorsal and ventral respiratory groups do?
medullary rhythmicity (initiation of breathing)
the respiratory centre
what type of nuclei does the dorsal respiratory group have and where is it found anatomically in the medulla
- has inspiratory nuclei
- found in the dorsal (posterior) section of medulla
the respiratory centre
what type of nuclei do the ventral respiratory groups have and where are they found anatomically
has inspiratory and expiratory groups
- VRGs are found bilaterally and ventrally (anterior) in the medulla
where are the pneumotaxic and apneustic centres found and state which one is inhibitory and which one is excitatory?
Pneumotaxic centre:
- upper pons
- inhibitory (limits depth of inspirtation which increases rate of breathing)
apneustic centre:
- lower pons
- excitatory
THe repiratory centre
what is the main function of:
- Pneumotaxic centre
- Apneustic center
Pneumotaxic centre:
- control rate and depth of breathing (limits inspiration)
Apneustic centre:
- modulates (smooths) breathing cycle to stop things like abrupt halts in inspiration and integrates inspiratory cutoff
the respiratory centre
where does the pneumotaxic centre feed into
feeds into the DRG
DRG
what nucleus is the dorsal respiratory group found in
the Nucleus tractus solitarius
DRG
where is the Dorsal respiratory group located anatomically
dorsally (posteriorly) in the medulla
Dorsal respiatroy group (DRG) - medulla
what do the nuclei in the nucleus tractus solitarius drive
drives breathing movements and timing
DRG
what 4 structures does nucleus tractus solitaris get sensory information from?
Think: 2 types of receptors
2 types of nerve
- Chemoreceptors
- proprioceptors
- vagus nerve
- glossopharyngeal nerve
DRG
where does the nucleus tractus solitarius output to?
outputs to inspiratory muscles
DRG
outline the nature of the action potentials from the nucleus tractus solitarius to the inspiratory muscles
repetitive “ramped” bursts of inspiratory neuronal action potentials for 2 secs, allowing inspiration, and then 3 seconds off, allowing for expiration
Ventral Respiratory Group (VRG)
where is the VRGs compared to:
- the medulla
- DRG
either side of medulla and anterior and lateral to the DRG
VRG
which 2 nuclei is the VRG located in
located in:
- nucleus para-ambiguus
- nucleus retroambiguus
where does the nucleus para-ambiguus supply?
- Laryngeal muscles
- pharyngeal muscles
where does the nucleus retroambiguus supply
diaphragm and external intercostal muscles
VRG
what does the VRG contain nuclei for?
both inspiratory and expiratory nuclei
VRG
what type of breathing is VRG involved in?
- active inspiration
- active expiration (ie: voluntary forced exhalation)
VRG
when in the VRG inactive
inactive in normal quiet breathing
VRG is inactive in normal breathing and only activates in ACTIVE breathing
VRG
what places do the nucleus retroambiguus and the nucleus para-ambiguus in the VRG feed into
Nucleus retroambiguus:
- diaphragm and external intercostal muscles
Nucleus Para-ambiguus:
- Laryngeal and pharyngeal muscles
Central pattern generation
what are the 3 phases of central pattern generation for breathing
- inspiratory phase
- post inspiratory/expiratory phase 1
- expiratory phase II
central pattern generation
what neurotransmitters are associated in central pattern generation in breathing
- NDMA
- GABA
central pattern generation
where are neurones with different firing patterns concentrated near in breathing?
concentrated near pre-Botzinger complex
efferent pathway from the respiratory centres
what spinal tract come from the respiratory centres in breathing
Bulbospinal Tract
efferent pathways from respiratory centres
where does the phrenic nerve originate from?
rootlets formed from cervical spinal nerves C3,C4 and C5
C3, C4, C5 keep the diaphragm alive
efferent pathway
where do intercostal nerves exit and where do they provide input to?
- exit thoracic and lumbar spine
- provide input to the intercostal and abdominal muscles
efferent pathways
what does the phrenic nerve do and where does it originate
- gives motor control to the diaphragm
- formed by rootlets coming from cervical spine C3,C4,C5
C3, C4, C5 keep the diaphragm alive
Pneumotaxic centre (upper pons)
outline the 3 steps of how pneumotaxic centre stops the lungs becoming too full
think:
- inhibitory impulses
- limiting activity of 2 places
- what this leads to
- Pneumotaxic centre sends continual inhibitory impulses to inspiratory centre in DRG of medulla oblongata
- this limits activity of phrenic nerve and inhibits apneustic centre
- this decreases the tidal volume which prevents the lungs becoming too full
Pneumotaxic centre
what happens in you stimulate the pneumotaxic centre more vs if you stimulated less
stimulated more: breathe fast and shallow
Stimulated less: inspiratory depth increases and slower breaths
apneustic centre
what does overstimulation of the apneustic centre do and how?
causes apneusis (gasping) by exciting inspiratory neurones, prolonging inspiration
what happens if there is damage to the apneustic centre?
respiratory cycle is abrupt (no smoothness)
what 2 things inhibits the apneustic centre?
- Stretch receptors at (max inspiration)
- Pneumotaxic centre
PNeumotaxic centre
what happens if you have upper pons damage
Deep long breaths as pneumotaxic centre is most likely damaged.
What 2 nerves is the nucleus tractus solitairus a sensory terminal for and what do these nerves do?
2 nerves:
- vagus
- glossopharyngeal
These nerves transmit sensory signals from different receptors to therespiratory centre
outline where the bulbospinal inspiratory neurones start, descend to and where they end
descend: from respiratory centre to the anterolateral column of the spinal cord
terminates: in anterior horn of cervical and thoracic vertebral segments.
