05.1 Chemical Control of Breathing Flashcards
Why isn’t PO2 tightly controlled?
PO2 can drop to below 8kPa before saturation drops
What can happen if pH drops below 7?
Enzymes become denatured
Death
What can happen if pH rises about 7.6
Free calcium drops
Tetany
What causes respiratory acidosis?
Hypoventilation
What causes respiratory alkalosis?
Hyperventilation
How is a respiratory acidosis or alkalosis compensated for?
Kidneys increasing or decreasing plasma HCO3- respectively
Takes roughly 3 days
What causes a metabolic acidosis?
Decrease in HCO3-
What causes a metabolic alkalosis?
HCO3- increasing
How are metabolic acidosis and alkalosis compensated for?
Increasing or decreasing respiratory rate respectively.
Where are peripheral chemoreceptors located?
Carotid and aortic bodies
What are peripheral chemoreceptors sensitive to?
PO2
What are central chemoreceptors sensitive to?
PCO2
How do central chemoreceptors work?
CO2 diffuses into the CSF.
H+ then diffuses back to the chemoreceptors in the ECF.
The pH is then used to estimate CO2 levels.
What is the response to persisting hypoxia and hypocapnia? (Type 1 resp failure)
Peripheral chemoreceptors detect hypoxia causing an increase in respiration.
CO2 falls further.
CSF compensates so that central chemoreceptors accept the low PCO2 as normal.
What is the response to persisting hypoxia and hypercapnia? (Type 2 resp failure)
Central chemoreceptors adjust pH so that the high CO2 levels are seen as normal.
PO2 is now the main stimulus for breathing (do not give O2 via mask.)
