control of ventilation Flashcards
what does ventilatory control require the stimulation of?
skeletal muscle of inspiration
what does ventilatory control occurs via?
phrenic (to diaphragm) and intercostal nerves (to intercostal muscles)
what are respiratory centres
pons and medulla
is ventilatory control subconcious?
yes
what is ventilatory control dependent on?
signalling from the brain
what do resp centres have their rhythm modulated by?
emotion
voluntary over-ride
mechano-sensory input from the thorax
chemical composition of the blood- detected by chemoreceptors
what are the functions of central chemoreceptors in the medulla?
Detect changes in [H+] in CSF around brain
Cause reflex stimulation of ventilation following rise in [H+]
what is ventilation inhibited by?
a decrease in arterial PCO2
what crosses the blood brain barrier if arterial PCO2 increases?
carbon dioxide not H+
where does central chemoreceptors monitor the the PCO2 indirectly
cerebrospinal fluid
does decreased arterial PCO2 speed up or slow ventilation rate?
slows
what increases ventilation in response to increased arterial PCO2?
feedback via resp centres
where are peripheral chemoreceptors located?
carotid and aeortic bodies
what is the function of peripheral chemoreceptors?
detect changes in arterial PO2 and H+
Cause reflex stimulation of ventilation following significant fall in arterial PO2 (consider haemoglobin dissociation) or a rise in [H+]
does peripheral chemoreceptors respond to arterial PO2 or oxygen
PO2
what does an increase in H+ usually follow a rise in?
arterial PCO2
does changes in the plasma pH alter ventilation? via what pathway?
yes via the peripheral chemoreceptor pathways
what happens to ventilation if plasma pH falls ?
ventilation will be stimulated (acidosis)
where would you find central chemoreceptors?
medulla
what are the main differences between central and peripheral chemoreceptors?
location- medulla / carotid and aortic bodies
response - directly to H+ / primary to plasma and PO2
ventilatory drive - primary / seconday
do central chemoreceptors respond to changes in plasma H+?
no
what controles our rate of breathing and depth of respiration?
respiratory centres
what are the two respiratory centres?
pons and medulla
what are the different types of respiration groups?
dorsal
ventral
pontine
what are dorsal resp groups for?
output primarily to inspiratory muscles
whats the ventral resp group for?
output to expiratory, some insp,
where is resp rhythms modulated by emotion?
limbic system in the brain
which chemoreceptor is less sensitive to CO2?
peripheral
what is CSF
interstitial fluif in the brain and is very heavily monitored
when is there a reflex simulation of ventilation in central chemoreceptors?
following a rise of H+
what is hypercapnea?
rise of PCO2
what protects the csf?
blood brian barrier
what cant pass through blood brain barrier
ions
what will happen to resp rate in an anaemic patient with a blood oxygen content half the normal value
stay the same
can you override involuntary stimuli such as arterial PCO2 or H+
no
how is ventilation inhibited?
increase in arterial PO2 or a decrease in arterial PCO2
when is respiration intentionally inhibited?
during swallowing
