Control of Respiration Flashcards
what has the main influence on breathing
CO2
what is the pre-Botzinger group
pacemaker cells in superior ventral respiratory group that act as breathing rhythm generator
what acts as the breathing rhythm generator
pre-Botzinger group
what does the pons respiratory group do
regulates some normal discharges of breathing
what are the 2 parts of the pons respiratory group
pneumotaxic and apneustic centres
what does the pneumotaxic centre do
puts brakes on breathing
what does the apneustic centre do
moderates effects of pneumotaxic centre - but can be overruled by pneumotaxic centre
stimulates DRG
what is the role of the medulla oblongata in respiration
phasic discharge of action potential
what are the 2 main groups of the medulla oblongata
dorsal respiratory group and ventral respiratory group
what is the general structure of the DRG and VRG
bilateral
project into bulbo-spinal motor neuronpools and interconnect
when is the DRG predominantely active
inspiration
what does DRG stand for
dorsal respiratory group
what is the DRG
group of inspiratory neurons in the medulla that stimulate diaphragm and external intercostals and send signals to VRG
what does VRG stand for
ventral respiratory group
when is the VRG active
inspiration (forced) and expiration
what does the VRG do
stimulates accessory muscles of ventilation and inhibits apneustic centre
what does the central pattern generator do
starts stops and rests background ventilatory drive
is inspiration active or passive
active
is expiration active or passive
mainly passive, with elastic recoil of thoracic wall
1st part involves active slowing with some inspiratory muscle activity
what is minute ventilation
proportional to PaCO2
Inversly proportional to oxygen i.e.e 1/PaO2
what is the value of minute ventilation
approx. 5l
what do chemoreceptors sense
PaCO2
what is the primary influence on brainstem chemoreceptors
PaCO2
what influences carotid and aorta chemoreceptors
PaCO2, PaO2, pH
where are central chemoreceptors found
in brainstem at pontomedullary junction - not DRG/VRG complex
what do central chemoreceptors detect
H+ in CSF; present through dissociation of CO2 which diffuses through BBB
what do central chemoreceptors do
provide excitatory synaptic input to the medullar inspiratory neurons
what do peripheral chemoreceptors detect
O2, CO2, H+
where are peripheral chemoreceptors found
bifurcation of CC arteries and arch of aorta
are peripheral chemoreceptors the same as arterial baroreceptors
no - close but distinc
where are carotid bodies found
common carotid arteries
what are carotid bodies
main peripheral chemoreceptors involved in control of respiration
what nerves are peripheral chemoreceptors linked to
CN 9 and 10 - send afferent fibres to higher brain centres
what cells are present in peripheral chemoreceptors
specialised receptor cells that are mainly stimulated by a decrease in arterial pO2 and increase in arterial [H+]
what does hypoxia do with peripheral chemoreceptors
type 1 cells release stored neurotransmitter that stimulates the carotid sinus neve and sends excitatory synaptic input to medullary inspiratory neurons
what are the types of pulmonary receptors
slowly adapting stretch receptors
rapidly adapting stretch receptors
irritant receptors
c-fibres J receptors (juxtapulmonary receptors)
describe the properties of slowly adapting stretch receptors
myelinated
maintain a persistent or slowly decaying receptor potential during constant stimulus
where are slowly adapting stretch receptors found
airway smooth muscle
what activates slowly adapting stretch receptors
lung distention
what is the Hering-Breuer reflex
reflex triggered to prevent over-inflation if lung - uses slowly adapting stretch receptors in airway smooth muscle
what is the effect of activation of slowly adapting stretch receptors
high activity inhibits further inspiration this beginning expiration
describe rapidly adapting stretch receptors
myelinated
generate a receptor potential and action potential at the onset of a stimulus - very quickly cease responding
where are rapidly adapting stretch receptors found
between airway epithelial cells
what activates rapidly adapting stretch receptors
lung distention and irritants - respond to rate of change in volume and irritants
what do rapidly adapting stretch receptors do
produce brief burst of activity - high activity causes bronchoconstriction
- may be involved in cough reflex
where are irritant receptors found
larger conducting airways
what are the properties of irritant receptors
rapidly adapting - cough, gasp
describe c-fibres j receptors (juxtapulmonary receptors)
non-myelinated
where are c-fibres J receptors (juxtapulmonary receptors) found
capillary walls or interstitium
what activates c-fibres j receptors
increase in interstitial pressure (e.g. collection of fluid), irritants, lung volume, noxious agents
what is the effect of c-fibre j receptor activation
rapid shallow breathing, bronchoconstriction, cardiovascular depression and dry cough
