Blood Gas Transport

Question 1

Dissolved oxygen and Hb-bound oxygen

Answer 1

Dissolved - much less so than Hb-bound…PaO2*SolubilityO2

Hb-bound - 70 times more O2 than the dissolved O2 in the arterial blood

Question 2

O2 content and tension

Answer 2

Content - concentration in the blood…dissolved plus Hb bound

Tnesion - partial pressure of oxygen in the blood

Question 3

In a gas mixture, partial pressure of a component gas

Answer 3

Px=Ptotal*Fx

Ptotal is ambient pressure

In alveolar gas, the alveolar air is always saturated with H2O vapor…this lowers the Ptotal

Question 4

IN blood, the partial pressure

Answer 4

Of a component gas is the same as that in a gas mixture when the gas mixture is in equilibrium with the blood

Question 5

Arterial and mixed venous blood PO2 and Co2

Answer 5

PO2 is higher in arterial blood (100 vs. 40)

cO2 - higher in arteiral blood (20 vs. 15)

mixed venous blood - blood in the right side of the heart

Heart - venous blood coming out is around 23…pretty low

SKin - about 60…pretty high

They all mix together in the right side of the heart

Question 6

Oxygen equilibrium curve

Answer 6

Relationship bt concentration of O2 and the partial pressure

arterial - in the plateau region

venous - at the end of the steep region

Question 7

Significance of the shape of the curve

Answer 7

If you go to higher altitidue, then the partial pressure wil drop…this won;t have a huge effect on the arterial content or the hemoglobin saturation…ensures that the amount of oxygen delivered is still relatively normal

If you exercise, it will drop the the PO2 from about 40 to 30…this will have a much greater effect on the O2 content of the venous blood…means that you can deliver MORE oxygen to the tissues

Question 8

O2 capacity and saturation

Answer 8

Maximal amount of O2 that CAN be combined with Hb in blood
Capacity = Hb concnetration times 1.36

Percentage of O2 capacity that is occupied by O2

So2 = (O2 combined with Hb/O2 capacity)*100%

Question 9

Effect on curve of anemia

Answer 9

If hemoglobin cut in half, then the O2 content is cut in half

The % of Hb saturation would still be the same (100%) at PO2 of 100

Question 10

P50

Answer 10

The O2 partial pressure needed to reach 50% Hb saturation

Question 11

Mechanism of Bohr effect and importance

Answer 11

Affinity of H+ ions for reduced Hb is greater than that for oxygenated Hb

Facilitates the O2 uptake in the alveolar caps and the O2 delivery in periphral tissue

Question 12

What would increase DPG?

Answer 12

RBC metabolism in chronic lung dz

Question 13

How is CO2 transported in the blood

Answer 13

Bicarb (tissue and plasma)
Dissolved CO2 (tissue)
Carbamino-Hb (Tissue, plasma, and RBC)

Question 14

Distribution of CO2

Answer 14

Aterial blood - 90% bicarbonate ions

A-V difference - most in bicarb…then carbaminoHb, then dissolved CO2

Question 15

CO2 curve

Answer 15

For a given PCO2, CO2 content of blood increases as PO2 falls (haldane effect)

Question 16

CO2 tension and content in artierla and mixed venous blood

Answer 16

Arterial - PCO2 lower (40 vs 46)

Mixed venous - CCO2 higher (52 vs 48)

Question 17

Haldane effect

Answer 17

Reduction in Hb-O2 sat in the blood causes upward shift of CO2 dissociation curve

Question 18

Mech and importance of the haldane effect

Answer 18

Reduced Hb is less acidic than oxygenated Hb therefore it can bind mroe easily with CO@ to form carbamino hemoglobin

Increase CO2 unloading in alveolar capillaries and CO2 uptake in peripheral tissue…makes it easier to take away in the tissues and let go in the lung