Lecture 8-Chemical Control of Breathing Flashcards
Define hypoxia
Fall in pO2
Define hypercapnia
Rise in pCO2
Define hypocapnia
Fall in pCO2
Define hyperventilation
Increased ventilation without change in metabolism - increased pO2 and decreased pCO2
Define hypoventilation
Decreased ventilation without change in metabolism - decreased pO2 and increased pCO2
How does hyperventilation affect pH?
Decreases pCO2 -> rise in pH
How does hypoventilation affect pH?
Increases pCO2 -> fall in pH
What are the acute effects on ventilation of a falling inspired pO2?
- increased breathing
- changes in HR and blood flow distribution
What are the acute effects on ventilation of increases in inspired pCO2?
Increase ventilation
Where are peripheral chemoreceptors found?
Carotid and aortic bodies
True or false: peripheral chemoreceptors are sensitive to changes in pCO2
FALSE
Where are central chemoreceptors found?
Medulla of the brain
What do central chemoreceptors do?
Respond to changes in pH of CSF
What is the CSF [HCO3-] controlled by?
Choroid plexus cells
What corrects persisting changes in CSF pH?
Choroid plexus cells which change [HCO3-]
Describe the effect of persisting hypoxia on the CSF
- hypoxia detected by peripheral chemoreceptors to increase ventilation but pCO2 will fall and ventilation will then decrease
- CSF choroid plexus cells add H+ or HCO3- into CSF and central chemoreceptors accept this pCO2 as normal
Describe the effect of persisting hypercapnia on the CSF
- peripheral and central chemoreceptors stimulate breathing but acidic pH is undesirable for neurons
- choroid plexus cells need to adjust pH of CSF by adding HCO3- and central chemoreceptors will accept this high pCO2 as normal