Week 4 - Carbon Dioxide Flashcards
Does CO2 react with haemoglobin?
Yes but at a different site to oxygen
How much carbon dioxide is the in arterial blood compared to oxygen and why?
2.5 times more carbon dioxide than oxygen because its more soluble and reacts chemically with water so theres more dissolved and reacted
What is the total content of carbon dioxide in arterial blood?
21 mmol/L
Why is there so much carbon dioxide going to the tissues?
Has a major role in controlling blood pH
What does carbon dioxide form when its reacted with water?
Carbonic acid
What happens to the carbonic acid that is formed by carbon dioxide reacting with water?
Very quickly dissociates into H+ and bicarbonate ions
This reaction is reversible depending on reactants and products
What happens if pCO2 rises?
Plasma pH will fall as reaction will favour the forward direction
What happens if pCO2 falls?
Plasma pH will rise as the reaction will reverse
What is the determining factor of pCO2 in the plasma and how is this controlled?
The pCO2 of the alveoli
Controlled by breathing
What is the plasma concentration of bicarbonate?
25 mmol/L
What is the cation most associated with bicarbonate?
Sodium (not H+)
What does high bicarbonate concentrations do to the pH of the plasma?
Prevent nearly all dissolved CO2 from reacting so pH of plasma is alkaline
Where are these high levels of bicarbonate produced?
Red blood cells
How does the bicarbonate leave the red blood cells?
Chloride bicarbonate exchanger
How is bicarbonate produced in RBCs?
CO2 + H2O H+ + HCO3-
