Control of Ventilation Flashcards
In neural control of ventilation, what type of receptors are involved?
Lung stretch receptors
In chemical control of ventilation, what type of receptors are involved?
Central and peripheral chemoreceptors
Which are of the brain is involved with ventilation?
What is this area of the brain called?
In the pins and medulla, located within the respiratory centre (also called central pattern generator).
What X2 areas that are connected with breathing are located within the pons, and what do they each do?
They are the pneumotaxic and apneustic centres, which are both involved in inspiration.
Pneumotaxic = inhibits inspiration
Apneustic = prolongs inspiration
What X3 areas that are connected with breathing are located within the medulla, and what do they each do?
1) dorsal respiratory group within the nucleus tractus solitarius.
= these are the inspiratory neurons of normal “quiet” breathing and relay the message to the phrenic nerve
= cease of firing of these neurons causes passive expiration
= the DRG receives both lung receptor and chemoreceptor input
2) ventral repsiratory group within the nucleus ambiguus and nucleus retroambiguus
= INACTIVE during normal quiet breathing
= these neurons fire during active breathing, both for inspiratory and expiratory muscles (but show reciprocal inhibition = one inhibits the other so they can not oppose and summate at the same time)
3) pre-bötzinger complex within the nucleus retrofacialis
= centre of respiratory rhythmogenesis
What pathway do we use for voluntary breathing if we want to override our central pattern generator?
The pyramidal tracts.
What are the X4 types of lung receptors?
1) stretch
2) juxtapulmonary (J)
3) irritant
4) proprioreceptors
Where are the lung stretch receptors found?
Within the smooth muscle of the bronchiole walls
Explain the deflation reflex.
Deflation stimulates inspiration.
Where are the juxtapulmonary (J) receptors located?
In the alveolar/bronchial walls close to the capillaries.
Which receptors are responsible for the deep augmented breaths we take every 5-20 minutes and why?
The irritant receptors responding to the gradual/slow collapse of the lungs over time during quiet breathing.
Where are proprioreceptors located?
In the respiratory muscles.
Where are irritant receptors found?
All throughout the airways.
What is the relationship graphically between PACO2 and ventilation?
They are linear; as PACO2 increases so does ventilation to match.
At the extremes this relationship ‘tails off’.
NB: ventilation in these graphs is not the same as respiratory rate, it is a volume measured in L/min.
What happens to the ventilation-PACO2 graph line to compensate for metabolically derived changes in pH?
It shifts to the right or left accordingly to compensate is respiratory effort.
E.g. metabolic acidosis/alkalosis with compensatory respiratory acidosis/alkalosis…
What is the relationship graphically between PAO2 and ventilation?
Anything above 8kPa PAO2, ventilation stays at a controlled 8-10L/min.
As PAO2 drops below 8kPa, it begins to stimulate ventilation increases steeply.
What does hypercapnia do to the PAO2-ventilation graph line?
It moves it upwards, meaning the same relationship exists with PAO2 and ventilation however for the same PAO2 the ventilation volume seen is higher.
What is meant by hypoxia and hypercapnia working synergistically?
The effect of the two of them together is stronger than separately.
What do central chemoreceptors respond to?
Changes in the pH of CSF, as the blood H+ ions can not cross the blood-brain barrier to the chemoreceptor.
They also respond to PaCO2 as gasses can cross the blood-brain barrier.
Where are the peripheral chemoreceptors found?
In the:
1) aortic bodies (in the aortic arch)
2) in the carotid sinus (where the common carotid artery bifurcates)
Which nerves innervate the:
1) aortic bodies
2) in the carotid sinus
1) the vagus
2) the glossopharyngeal
What are the X2 cell types which are found in the carotid bodies?
Type 1 glomus cells
Type 2 sheath cells
= party enclose around type 1 cells
What do aortic and carotid bodies respond to?
Increases in PCO2
Decreases in PO2
Increase in pH
What condition leads to periods of progressive, faster breathing followed by long periods of apnea, which results in the rise and fall of O2 saturations?
Cheyenne-stokes respiration
What is the main difference between central and obstructive sleep apnoea?
In obstructive, the airways collapse but a respiratory effort still remains.
In central, it is the respiratory effort which stops.
What condition is a for, of brainstem damage which results in respiratory arrest during sleep?
Ondine’s curse.
