Neuroanatomy of Breathing Flashcards
What nerves give peripheral chemoreceptor feedback?
hypoglossal
laryngeal
carotid sinus
What nerve regulates breathing frequency and volume?
vagus
What nerves control respiratory muscles?
intercostals
What nerve controls diaphragm inspiration?
phrenic
What are the inspiratory muscles?
sternocleidomastoid scalenes external intercostals parasternal intercostals diaphragm
What are the expiratory muscles?
internal intercostals external abdominal oblique internal abdominal oblique transverse abdominals rectus abdominis
How do the abdominal wall muscles aid in expiration?
push gut up against diaphragm
what are the cranial motorneurons important for?
opening and closing the glottis, affecting upper airway diameter and nostril flaring
Where is the central pattern generator?
the pons and the medulla
What is contained within the pons respiratory center?
pneumotaxic center
apeustic center
What is followed before the medulla?
the pre-botzinger complex
What is found in the medullary respiratory center?
dorsal respiratory group
ventral respiratory group
What is the dorsal respiratory group involved with?
inspiration
What is the ventral respiratory group involved with?
inspiration and expiration at the top and bottom
Where is the dorsal respiratory group found?
in the nucleus tractus solitarius
What is the dorsa respiratory group the site of?
sensory input
central chemoreceptor input
What are the three regions of the ventral respiratory group?
rostral
intermediate
caudal
What is contained in the rostral region?
nucleus retrofacialis - expiration
What is contained within the intermediate region?
Pre-botzinger and the nucleus ambiguus, nucleus para-ambigualis - inspiration
What is the pre-botzinger though to be?
the respiratory pattern generator
What is contained within the caudal region?
the nucleus retroambigualis - expiration
What happens to breathing when sections above the pons?
normal when vagus intact
slow and deep when vagus cut
What happens to breathing when superior pons is cut?
slow and deep breathing with vagus intact
apneusis when vagus cut
What happens when all the pons is cut?
irregular rhythm with vagus intact
irregular and infrequent rhythm when vagus cut
What happens when the pons and medulla are cut?
apnea
What tells us that there is a heirachy of neural inputs into control of breathing?
sectioning of brain stem with vagus intact produces a decrease in breathing depth and frequency
What tells us there are neural feeback loops controlling frequency, rhythmicity and depth?
cutting the vagus nerve produces a variety of effects on the heirarchy
What tells us there are feedback interactions between several nerves which contribute inter-dependently to breathing pattern?
the varied effects of cutting the vagus can only be explained by input from other neural networks
What is a respiratory rhythm generator?
a network of interneurons that produce a predictable and repetitive motor pattern
What are the properties of an RRG?
always active even in the absence of conscious input
Transmit in an orderly sequence
Response to inputs from other parts of the brain as well as sensory afferents
What are the 3 phases of the breathing cycle?
inspiration
post-inspiration
late-expiration
What are the 6 types of neuronal discharge?
pre-I early -I I Late-I early -E E
What does Pre-I do?
inhibits expiratory neural circuit and causes expiratory muscles to relax
What does Early-I do?
inhibits output from entire RRG causing a refractory period
What does I do?
ramp fire increasing frequency and recruiting more I neurons - inhibit E and pre-I - inspiratory muscles contract and exp muscles relax
What does Late-I do?
feed back to suppress I signalling which may involve stretch receptor input from vagus - insp muscles relax and lung begins to deflate due to elastic recoil
What does Early E do?
repress all I and E firing - creates refractory period at peak inhalation - lung deflates as insp muscles relax
What does E do?
ramp fire and activate exp muscles…major conscious input into breathing - exp muscles contract as insp muscles relaxed
What does RRG activity vary in relation to?
tidal volume
air flow
phrenic nerve activity
