6/7. Haemoglobin and Gas Transport Flashcards
Why does blood transport O2 from lungs to tissues?
To use in energy production
What is transported in the blood, as a waste product, from tissues to lungs?
CO2
What is the volume of O2 in Plasma?
3ml/L
What increases O2 carrying capacity to 200m/l in RBC?
Haemoglobin
How is the bulk of CO2 transported?
In solution in plasma
Are arterial partial pressure of O2 and arterial O2 concentration/content the same?
No
What does arterial partial pressure refer to?
Purely to O2 in solution and is determined by O2 solubility and the partial pressure of O2 in the gaseous phase that is driving O2 into solution
O2 is in equilibrium what does this mean?
The same amount of O2 is going to liquid as liquid going to gas
What is an air embolism?
When gases travel in the gaseous form in the plasma, causing bubbles
What does each litre of systemic arterial blood contain?
~200ml of O2 (More than 98% bound to Haemoglobin, while rest is in plasma)
How many molecules of O2 bind co-operatively to haemoglobin?
4 molecules (1.34ml of O2)
92% haemoglobin in RBC is in the form HbA, what is the remaining 8% made up of?
HbA2 (δ chains replace β)
HbF (γ chains replace β)
glycosylated Hb (HbA1a, HbA1b, HbA1c)
What is glycosylated Hb a good indicator of?
The exposure of sugar over the lifespan of haemoglobin and a persons blood glucose level
When does co-operative binding occur?
When O2 binds to haemoglobin and the affinity for O2 is increased
At which PO2 level does the affinity of haemoglobin begin to fall rapidly?
60mmHg
As there is little change in % of saturated haemoglobin above 60mmHg, what does this allow?
A relatively normal uptake of oxygen by the blood even when alveolar PO2 is moderately reduced
What is the percentage of arterial O2 is extracted by peripheral tissues at rest?
25%
What is the O2 demand of resting tissues?
250ml/min
What does Hb effectively do to O2 in plasma?
Sequester/Isolate
When is saturation complete?
After 0.25s contact with alveoli (total contact time is ~0.75s)
What is the equation for Hb oxygenation?
Hb + O2 HbO2
