Oxygen and Carbon Dioxide Carriage by the blood Flashcards
1
Q
Dalton’s Law
A
states that the total pressure exerted by the mixture of inert (non-reactive) gases is equal to the sum of the partial pressures of individual gases in a volume of air
so (total partial pressure = PN2 + PCO2 + PO2 + PH2O and others)
2
Q
Henry’s Law
A
states that the number of molecules dissolving in a liquid is directly proportional to the partial pressure of the gas
3
Q
structure of haemoglobin
A
- two alpha chains and two beta chains
- haem groups containing iron
4
Q
what is oxygen saturation?
A
Hb + O2 <-> HbO2
- 1g of Hb combines with up to 1.34ml O2
- oxygen capacity - the max amount of O2 that can combine with Hb - with 150g/L blood contains a max of 200ml/L O2 bound to Hb
oxygen saturation: (volume of oxygen bound to Hb (ml?l)) / (total oxygen capacity (ml/L)) x 100%
5
Q
2 forms of oxygen transport
A
- dissolved in plasma - 2%
- bound to Hb - 98%
6
Q
HbO2 dissociation curve
A
- much more than dissolved (x67)
- reserve on plateau - air travel, altitude, disease (alarming rapid progress, threshold phenomenon)
- amount of O2 given up going from lung tissue
- amount of O2 taken up going from tissue to lung
7
Q
HbO2 dissociation curve - decreased P50
A
- increased affinity
- decreased temperature
- decreased PCO2
- decreased 2,3-DPG
- increased pH
8
Q
HbO2 dissociation curve - increased P50
A
- decreased affinity
- increased temperature
- increased PCO2 (Bohr effect)
- increased 2,3-DPG
- decreased pH (Bohr effect)
cyanosis - visible appearance of hypoxia
9
Q
Oxygen carriage
A
- carried in 2 ways (dissolved and reacts with haem)
- approx 200ml/L
- plateau
- requires 7kPa to extract approx. 50ml/L at rest
- shifts in curve (Bohr effect plus other factors)
10
Q
Carbon Dioxide carriage
A
- carried 3 ways (dissolved, reacts with globin, mostly reacts with water)
- approx 500ml/L
- no plateau
- requires 0.7 kPa to add approx. 45 ml/L at rest
- shifts in curve (Haldane effect)
