In plasma, CO2 may facilitate the formation of hydrogen ions and hydrogen carbonate ions. Why is this reaction slow?
Little carbonic anhydrase in plasma
What is the dissolved concentration of CO2 in plasma at a pCO2 of 5.3kPa?
How is the hydrogen carbonate which is present in blood plasma formed?
In Red blood cells
reaction with CO2
Requires carbonic anhydrase
What happens to the pH if:
Write out the Henderson- Hasselbach equation.
Why is it important that In plasma the ratio of [HCO3-] to dissolved CO2 stays consistent?
[HCO3-] : CO2
As long as this ratio stays consistent, pH will be 7.4
What happens to the hydrogen ions which are formed from the reaction of CO2 with H2O in the presence of carbonic anhydrase? What does this cause?
Hydrogen ions bind to haemoglobin
Result: reaction drawn towards production of HCO3-
(Amount of CO2 produced largely depends on buffering capacity of haemoglobin, only minor effect due to change in pCO2)
How is the HCO3- exported from the red cell?
Exported in exchange for Cl-
Chloride bicarbonate exchanger
Name an organ in the body which has control over [HCO3-].
List all the forms in which carbon dioxide is carried in the blood:
(Carbamino compounds- formed by reaction of carbon dioxide with protein part of haemoglobin)
Why is haemoglobin a 'better buffer' in venous blood?
Haemoglobin less saturated with oxygen
What % of CO2 is transported in the blood in the form of:
- Dissolved CO2
- Hydrogen carbonate
- Carbaamino compounds
Why is it that hyperventilation reduces the CO2 content in the blood but has little effect on the oxygen concentration?
Relationship with pCO2 and CO2 is not sigmoidal. = almost linear (see graphs)
How much carbon dioxide is taken from tissues and given off (ie transported)? What function does the rest of the carbon dioxide in the blood serve?
Other CO2 acts as buffering system