Chemical control of ventilation Flashcards
What do chemoreceptors detect
Changes in arterial;
- pCO2
- pO2
- [H+]
does oxygenated blood have more [H+] or deoxygenated
oxygenated
Where are central chemoreceptors found
Medulla
What are central chemoreceptors sensitive to
Changes in;
[H+] and pCO2
Where are peripheral chemoreceptors found
Within aortic arch and carrot arteries
What are peripheral chemoreceptors sensitive to
Changes in;
arterial pO2 and pH
How are CCRs (central chemoreceptors) activated
- Blood brain barrier impermeable to H+ and HCO3- but permeable to CO2
- Increase in partial pressure of CO2 causes it to diffuse out of the blood vessel
- H+ ions are formed from a reaction
- Increase in the concentration of H+ in extracellular fluid and cerebrospinal fluid is detected by central chemoreceptors and leads to hyperventilation
- Hyperventilation decreases PCo2 in blood and cerebral spinal fluid
- decreases in PCO2 leads o hyperventilation
What does a decreased arterial O2 do in peripheral chemoreceptors
Hyperventilation
-stimulated when arterial pO2 falls below a certain level
What does an increase in PCO2 mean in peripheral chemoreceptors
Not as important as CCR
Where is a fall in pH detected
By carotid peripheral chemoreceptors but not aortic bodies
what does hypoventilation cause
Respiratory acidosis
What does hyperventilation cause
Hyperventilation
What is increased in hypoventilation
[H+] excretion
[HCo3-] reabsorption
In kidneys
What is increased in hyperventilation
[H+] reabsorption
[HCo3-] excretion
in kidneys
How does diabetes affect ventilation
In uncontrolled diabetes, there is a decrease in the ability of kidneys to excrete H+ and reabsorb HCO3-
To compensate, there is an increase in ventilation which leads to a decrease in arterial partial pressure of CO2
