Respiratory Control of Ventilation Flashcards
What provides chief baseline control of respiration?
Brainstem “pacemakers”
What are the chief inputs to the brainstem “pacemakers”?
- pH in the cerebrospinal fluid
- Pco2 in the periphery
- Po2 in the periphery
- pH in the periphery
What do medullary pH sensors monitor?
Arterial Pco2
How do medullary pH sensors monitor arterial Pco2?
By Pco2’s influence on CSF acidity (carbonic anhydrase).
What senses Pco2?
Carotid and aortic bodies
What senses Po2?
Carotid bodies
What senses arterial pH?
Carotid bodies
What can cause an increase in breathing?
High Pco2 or low Po2/pH.
What variable is most relevant for day-to-day control of ventilation?
CO2
What is important in altitude adaptations and in chronic lung disease?
O2
What is the mechanism of exercise-induced hyperventilation?
Unknown
What are three major feedback mechanisms for control of ventilation?
- Central controller
- Peripheral sensors (chemoreceptors)
- Efferent mechanisms (nerves and muscles)
Where is the central controller?
Brainstem (pons and medulla)
What can panic attacks do to the Pco2?
They can halve the Pco2 as a result of doubling the respiration rate!
What is the most important sensor in day-to-day regulation of ventilation?
Central chemoreceptors
–> they respond to pH
What are the peripheral chemoreceptors and what do they respond to?
Aortic arch and Carotid bodies.
-Respond to Pco2, pH and Po2
What are the lung receptors?
- Stretch receptors
- Irritant receptors
- J receptors
- Bronchial receptors
How do Central pH receptors relate to respiration?
- H+ stimulates respiration
- Alkalosis suppresses respiration
What surrounds Central pH receptors and what determines the pH there?
Bathed by cerebrospinal fluid (CSF)
- H+ cannot cross the BBB
- CO2 diffuses across and is converted to carbonic acid
What determines CSF pH? What is the normal CSF pH?
Plasma CO2, 7.32
How is CSF acidosis compensated for?
By HCO3 retention by the CSF
–>Can be observed in patients with emphysema having extremely low Po2 and high Pco2 and relatively low respiration rates because of this compensation
