Week 5 - Chemical Control Of Breathing Flashcards
What is the function of the respiratory system?
Maintaining oxygen and CO2 partial pressure gradients to optimise transfer and regulate pH of extracellular fluid
What is hypercapnia?
Fall in pCO2
What is hypoxia?
Fall in pO2
How do we control pO2 and pCO2 in exercise?
pO2 drops and pCO2 rises
Breathing more will restore both their normal levels
What is hyperventilation?
Ventilation increase without change in metabolism
What is hypoventilation?
Ventilation decrease without a change in metabolism?
How will hyperventilation affect pO2 and pCO2 levels?
pO2 will rise
pCO2 will fall
How will hypoventilation affect pO2 and pCO2 levels?
pO2 will fall
pCO2 will rise
What will happen if pO2 increases without a change in pCO2?
Correction of pO2 will cause pCO2 to drop leading to hypocapnia
What is the major buffer system in the blood?
Carbonic acid-bicarbonate buffer system
Why is the carbonic acid-bicarbonate buffer system so effective?
Amount of dissolved CO2 is controlled by respiration
Bicarbonate concentration is regulated by kidneys
Bicarbonate is in equilibrium with CO2 so can be substituted for it
If bicarbonate remains unchanged and pCO2 increases what Happens to pH?
Falls - acidic
If bicarbonate remains unchanged and pCO2 decreases what happens to pH?
Rises - alkaline
What happens if pH falls below 7.0?
Enzymes become denatured
What happens if pH rises above 7.6?
Free calcium concentration drops leading to tetany
What is respiratory acidosis?
Fall in plasma pH due to increases in pCO2
What is respiratory alkalosis?
Rise in plasma pH due to decrease in pCO2
How is respiratory acidosis compensated?
Kidneys increasing bicarbonate
How is respiratory alkalosis compensated?
Kidneys decreasing bicarbonate
How long does it take for the kidney to compensate changes in pH?
2-3 days
What is metabolic acidosis?
Tissues produce acid during metabolism which reacts with bicarbonate
This leads to a fall in bicarbonate concentration and a fall in pH
How is metabolic acidosis compensated for?
Increasing ventilation lowers pCO2
Give an example of when plasma bicarbonate may rise?
After vomiting
How is metabolic alkalosis compensated for?
Decreased ventilatiom
Is controlling pO2 more important than controlling pCO2?
No, don’t need precise control of pO2 as long as it stays above 8 kPa
