Control of Respiration Flashcards
What would PaO2, SaO2, PaCO2, and A-a gradient do with low [Hb]?
they would all stay normal
What would PaO2, SaO2, PaCO2, and A-a gradient do with carbon monoxide poisoning?
all normal except SaO2 would decrease
Where is the respiratory center located?
the medulla
What does the output from the medulla control?
- motor neurons that control respiratory muscles
- changes in tidal volume
- changes in breathing rate
Where are peripheral chemoreceptors located?
the carotid bodies
What is the function of peripheral chemoreceptors?
increase ventilation in response to:
- decreased arterial O2
- increased arterial PCO2
- high arterial [H+]
Which type of receptors respond to changes in pH/[PaCO2] the fastest?
peripheral chemoreceptors
Where are central chemoreceptors located and what type of receptor is it?
located on the ventral surface of the medulla, H+ receptor
Where do the H+ ions come from that the central chemoreceptors sense?
CO2 crosses the BBB and causes bicarbonate formation and the release of H+ ions. Therefore, the H+ ions DO NOT come from the blood but instead from HCO3 in the brain from CO2 crossing the BBB
T/F the CSF has a high buffering capacity
False, it has a low buffering capacity
What is the most important day to day regulator of ventilation?
central chemoreceptors
What type of receptor mediates increase in ventilation when climbing Mt. Everest?
peripheral O2 receptors
What type of receptor mediates increase in ventilation with ketoacidosis?
peripheral proton receptors
What type of receptor mediates increase in ventilation when climbing stairs?
peripheral CO2 receptors
What type of receptor mediates increase in ventilation with bronchitis?
central proton receptors/CO2 sensors
what elements of blood in bronchitis could potentially mediate increase in ventilation?
CO2
Why are protons and O2 not major mediators of ventilation?
because H+ are buffered well in the blood and oxygen receptors are not very sensitive
Why is the initial recovery of PaO2 at high altitude incomplete?
- initially reduced CO2 leads to reduced H+ in the blood
- this leads to respiratory alkalosis due to decreased PCO2
- compensation: decrease in bicarb through reabsorption in kidney
- this leads to decreased [HCO3-] in the blood
- this creates a gradient of HCO3 from CSF to blood causing flow of HCO3 from the CSF to the blood
- this increases the [H+] in the CSF because HCO3 leaves (dilution)
- central chemoreceptors sense increased [H+] which results in increased ventilation turning it into a vicious cycle with more loss of CO2
