control of lung function Flashcards
where does control of lung function occur
medulla oblongata
there are 4 groups of _ that are important to the generational control of the intrinsic rate and rhythm of breathing
nuclei
what are the 4 groups of nuclei
dorsal respiratory group
ventral respiratory group
apneustic centre
pneumotaxic centre
what does the dorsal respiratory group do
- inspiratory centre
- main controller of inspiration
- set the “rate”
- posterior/dorsal
- works synergistically and antagonistically with ventral respiratory group
what does the ventral respiratory group do
- expiratory centre
- inactive during quiet breathing - not activating muscle
- inhibit apneustic centre
- more anteriorly
what does the apneustic centre do
- stimulates activity in DRG
- inhibited by pulmonary afferents
- associated with inspiration
what does the pneumotaxic centre do
the “inspiratory off switch”
- regulates depth and freq
associated with expiration
regulates depth and frequency
what does DIVE stand for
dorsal inspire
ventral expire
whats the tea between the groups
dorsal and ventral respiratory groups inhibit/inactivate each other
ventral inhibits apneustic centre
pneumotaxic inhibits DRG
apneustic stimulates DRG
describe quiet breathing
action potentials come in at given amplitude and set frequency
frequency increases until it activates the pneumotaxic centre
creates a cessation (stop of rhythm)
inspiration stops occuring
after a period of latency - the apneustic centre can program that rhythm into the dorsal RG
in between vertebrae there are..
spinal nerves
what do C3/4/5 spinal nerves become
one phrenic nerve - the main motor nerve that goes to the diaphragm
C3/4/5 keeps the diaphragm alive
what muscles are found between ribs
internal and external intercostal muscles
what muscles attach to lateral aspects of the ribs and are responsible for inspiration
external intercostal
what muscles are responsible for expiration
internal intercostal
does the blood brain barrier also have continuous capillaries
yes but a tight junction
what does carbon dioxide and water make
carbonic acid which then goes to protons and bicarbonate
what do the protons do
drive breathing as it is a product of metabolism
because protons and bicarbonate are charged, what can’t they do
unable to cross/diffuse over lipid bilayer of endothelial cells
as protons and bicarbonate exits in equilibrium with dissolved CO2 - what is CO2 able to do
freely diffuse across and can participate in equation - protons can now interact with afferent fibres in medulla > takes signal straight to DRG > determines rate and rhythm that should be created
can charged/large molecules cross the BBB
N O
is CO2 highly lipid soluble
hai
describe how protons get to the medulla to interact with afferent fibres in the medulla to DRG
H+ and bicarbonate cannot pass into CSF but CO2 can
CO2 in the CSF reacts with H2O to make protons and bicarbonate
protons can get to the medulla and interact with afferent fibres taking the signal to the DRG
what are some pulmonary afferents that affect ventilation
irritant receptors
stretch receptors
J receptors
what do irritant receptors do
detect any foreign matter leading to coughing
afferent receptors are embedded within and beneath airway epithelium
what is coughing
coughing is forceful expiration against a closed glottis with sudden glottal opening and high velocity expulsion of air
what do stretch receptors do
excessive inflation of the lungs activates pulmonary stretch receptors
sends afferent signals to respiratory centres to inhibit DRG and apneustic centre and stimulate pneumotaxic VRG
what do J receptors do
they are sensitive to oedema and pulmonary capillary engorgement
increasing breathing freq
what is volitional apnoea
ventilating a little arterial oxygen and CO2 are fairly stable breath hold no longer replenishing O2 decay of O2 steady accumulation of CO2 accumulation of protons beyond the BBB stimulating the medulla to breathe in CO2 threshold > struggle phase > ventilate
what is the definition of an acid
an acid is any molecule that has a loosely bound H+ ions that it can donate
why are H+ ions called protons
a H atom with a -1 valency has no electrons or neutrons
what happens when there’s a greater conc of H+
lower pH
why must the acidity of blood be tightly regulated
changes the 3D structure of proteins (enzymes, hormones, protein channels) - tertiary and quaternary
what is a base
an anionic (negatively charged ion) molecule capable of reversibly binding protons (to reduce the amount that are free)
equation for H2O and CO2 relating to H2CO3
H2O + CO2 <> H2CO3 <> H+ + HCO3-
how do you work out [H+]
[H+] = 10^-pH
what does alkalemia mean
refers to higher than normal pH of blood
what is acidaemia
refers to lower than normal pH of blood
what is alkalosis
describes circumstances that will decrease [H+] and increase pH
what is acidosis
describes circumstances that will increase [H+] and decrease pH
what can changes in ventilation stimulate
a rapid compensatory response to change CO2 elimination and therefore alter pH (ventilation)
what do changes in HCO3- and H+ retention and secretion do
in the kidneys - can stimulate a slow compensatory response to increase/decrease pH (metabolic)
what will an acidosis need to correct
an alkalosis
what will an alkalosis need to correct
acidosis
where are peripheral chemoreceptors
positioned near the carotid baroreceptors (sensitive to changes in blood pressure)
what do carotid bodies in the aortic arch do
provide feedback to brain
where are aortic bodies found
in aortic arch
where are specialised cells/chemoreceptors located
at the bifurcation of the carotid arteries in specialised places called carotid bodies
emotional change to ventilation
higher brain centres and special senses > emotional response > respiratory control centre
breathing during exercise
efferents from primary motor cortex to gross skeletal musculature partly innervate medulla
proprioceptive afferents from muscle spindles and golgi tendon organs innervate medulla on the way to the brain
belly of muscle and tendon
muscle fibres lengthening and shortening is picked up > stimulates ventilation
effects of skin afferents on breathing
cold surge - central reflex of deep breathing to do with nerve endings in skin immersion in cold water <10 degrees ventilatory inspiratory gasp/hyperventilation
