Flashcards in RESPIRATORY Deck (160)
what is the pre-botzinger complex?
pacemaker cells located in the superior ventral respiratory group
act as breathing rhythm generator
what is the apneustic centre?
it is the pontine centre that acts on dorsal respiratory group to adjust inspiration and increase inspiratory intensity
what is the pneumotaxic centre?
pontine group causing time dependent inhibition of the apneustic centre to allow expiration
what does increased innervation of the pneumotaxic centre result in?
increased innervation leads to shallower ventilation with increased frequency
what is the dorsal respiratory group?
in the medulla
inspiratory neurones that stimulate the diaphragm and external intercostals
what is the ventral respiratory group?
centre for forced inspiration and expiration
stimulates accessory muscles of ventilation and inhibits the apneustic centre
what is responsible for respiratory drive?
- pre-botzinger complex
- apneustic centre - pons
- pneumotaxic centre - pons
- dorsal respiratory group - medulla
- pneumotaxic respiratory group - medulla
- input to nucleus tractus solitarius and ambiguus from receptors and CN IX and X
apart from pontine and medullary respiratory centres, what can also control respiratory drive?
higher brain centres eg limbic system
drugs eg opioids
these can both suppress the respiratory drive
amphetamines increase respiratory drive
what is the normal minute ventilation and what can it expand to?
7.5L / min but can increase to 30L / min - large respiratory reserve
where are slow adapting stretch receptors (SASRs) found?
in smooth muscle of airways
what is the role of slow adapting stretch receptors (SASRs)?
inhibit inspiration in response to stretch (hering-breuer reflex) - protective
where are rapid adapting stretch receptors (RASRs) found?
in between airway epithelial cells
what is the role of rapid adapting stretch receptors (RASRs)?
they respond to rate of change of volume as well as irritants - possibly initiate cough as well as asthma exacerbations
also stimulate long, deep breathing
what is the role of juxtapulmonary receptors?
responds to irritants, lung volume, interstitial fluid volume and noxious agents
they cause bronchoconstriction, rapid and shallow breathing and reduced CO2
where are central chemoreceptors located?
at the pontomedullary junction in the brainstem
where are peripheral chemoreceptors located?
in the bifurcation of the carotid arteries (carotid sinus) and aortic arch
which nerves innervate the peripheral chemoreceptors?
carotid sinus = glossopharyngeal (CN IX)
aortic arch = vagus (CN X)
what do central chemoreceptors respond to?
they respond to changes in concentration of CO2 -
CO2 diffuses into CSF and dissociates into H+
what effect does increased CO2 concentration have on central chemoreceptors?
more CO2 diffuses into CSF and dissociates into H+
this increases H+ concentration and decreases pH of CSF
this increases action potential firing and increases ventilation rate
what is the dominant receptor in control of ventilation?
central chemoreceptors - detecting CO2 concentration
what do peripheral chemoreceptors respond to?
they detect changes in O2 concentration
they will only respond to PaO2 below 60-80mmHg
what effect does a decrease in O2 concentration have on peripheral chemoreceptors?
decrease in O2 conc. causes closes of K+ channels in type 1 glomus cells
causes depolarising and opening of Ca2+ channels cause release of noradrenaline
this causes increased action potentials through cranial nerves to increase breathing
why is there no peripheral receptor response if hypocapnic?
they only detect changes in O2 concentration
they wont respond to hypocapnia even if hypoxic and no response to acidosis if hyperoxic
peripheral chemoreceptors will only respond to PaO2 below 60-80 mmHg, but increased PaCO2 raises to PaO2 at which receptors are activated
what is the effect of prolonged hypoxia?
it can cause type II sustentacular cells to differentiate into type I to increase action potential firing to further stimulate ventilation
where do the lungs develop from?
the respiratory diverticulum - an outbranch of the foregut during weeks 4-5 (embryonic phase)
what is atresia?
failure of the trachea and the oesophagus to separate
when does pseudoglandular phase of lung development occur and what happens during this phase?
development of conducting airways
when does the cannalicular phase of lung development occur and what happens during this phase?
capillaries, vasculature and alveoli form
when does the embryonic phase of lung development occur and what happens during this phase?
lungs develop from respiratory diverticulum - outbranch of foregut