control of lung function Flashcards
name the 4 regions in the medulla oblongata
Dorsal respiratory group
Ventral respiratory group
Apneustic centre
Pneumotaxic centre
what is the dorsal respiratory centre
main function
Inspiratory centre
Main ‘controller’ of inspiration
Set the ‘rate’
where is it
posterior in the brainstem
Ventral respiratory group
function
Expiratory centre
how active/inactive is it during quiet breathing
Inactive during quiet breathing
what does the ventral re gr act on
Inhibit apneustic centre
where is it
posterior to the DRG
what is Apneustic centre
associated wuth
inspiration
what does it stimulate
DRG
how is it inhibited
Inhibited by pulmonary afferents
VRG
what is Pneumotaxic centre
associated with
expiration
what is the main function of the Pneumotaxic centre
The ‘inspiratory off switch’
Regulates depth & frequency
DIVE
Dorsal inspire
Ventral expire
how does the Pneumotaxic centre inhibit the apneuustic centre
apneustic centre stimulated DRG
action potential increases to a certain point/threshold then the Pneumotaxic centre
stops the ap
where do the phrenic (controlling diaphragm) nerves originate from
c3 4 5 nerves become
what are the external intercostal. muscle responsible for
inspiration
what are the internal intercostal muscle responsible for
expiration
difference between normal cappiliries and the blood brain barrier
normal capilliries are continous as are blood brain
difference is that BB have tight junctions help more tightly pack
what does that mean
the substances that can get into the csf from the blood are heavily restricted
how do protons and hco3- diffuse across the lipid bilayer
they can’t pass thru thr BBB
but co2 can and will as it is highly lipid soluble
once in the csf it will undergo the same reactions in the blood e.g. h20 + c02-> h+ +hco3-
which molecule out of those reacts with afferent fibres in the medulla
h+
what happens
project signals to dorsal respiratory group/nucleus to determine what type of rate or rhythm should be created
what receptors are there in the airways
Irritant receptors
Stretch receptors
J-receptors
where are Irritant receptors
Afferent receptors embedded within and beneath airway epithelium
function and what is it
Leads to cough: which involves forceful expiration against a closed glottis with sudden glottal opening & high velocity expulsion of air
what activates Stretch receptors
Excessive inflation of lungs activates pulmonary stretch receptors
what affect in the medulla
Afferent signals to respiratory centres inhibit DRG and apneustic centre and stimulate pneumotaxic VRG
what is thus the function
Inspiration inhibited & expiration stimulated
what are j receptors sensitive to
Sensitive to oedema and pulmonary capillary engorgement
what function do they carry out
Increases breathing frequency
what occurs when you hold your breath for a prolonged period of time
(when ventilating your arterial o2 and arterial co2 are stable) Not replenishing o2 o2 decreases co2 increases accumalation of h+ beyong the BBB stimulate the medulla to breathe in
does the blood buffer
The blood has an ENORMOUS buffering capacity that can react almost IMMEDIATELY to imbalances
Alkalaemia
Refers to high-than-normal pH of blood
Acidaemia
Refers to lower-than-normal pH of blood
Alkalosis
Describes circumstances that will decrease [H+] and increase pH
Acidosis
Describes circumstances that will increase [H+] and decrease pH
so alkalosis causes
alkalaemia
what are ventilatory distubances
changes in breathing that then cause a change in ph
then corrected by the kidneys
what are metabloic disturbaces
any non lung cause of change in ph (normally corrected by the lungs)
what is the time scale for changes in ventialtion
Changes in ventilation can stimulate a RAPID compensatory response to change CO2 elimination and therefore alter pH
describe the timescale for changes made by the kidneys
Changes in HCO3- and H+ retention/secretion in the kidneys can stimulate a SLOW compensatory response to increase/decrease pH
can emotion change breathing
yep
can exercise change breathing
yes, anything shortening you muscle stimulates increase ventilation
even if you move somelse e.g cycle their legs
what can immersing the body in cold water do
causes deep breathing
Ventilator
Inspiratory gasp/
hyperventilation
what pattern do respitory pacemakers display
Respiratory pacemaker displays a ‘ramp potential’ pattern
which 2 main nuclei are responsible for inspiration
Dorsal respiratory group and apneustic centre control inspiration
and expiration
Ventral respiratory group and pneumotaxic centre control expiration
what stimulates inspiration
Central H+ concentration, juxtacapillary oedema/pulmonary engorgement, motor control, limbic system, peripheral O2 concentration, peripheral proprioceptors and skin thermoreceptors
what causes expiration
Airway stretch receptors, limbic system, motor control
Coughing stimulated by airway irritant receptors
what ph is the blood between
Blood pH is tightly regulated between 7.35 and 7.45
