AAMC 6 'oxygenation question'

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ronaldo23

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Which of the following factors will NOT influence the oxygenation of blood in the pulmonary circulation?
A. Rate and depth of breathing
B. Hemoglobin concentration of the blood
C.Blood pressure in the pulmonary artery
D. Surface area of the alveoli


Answer is C, but wouldn't a very high blood pressure in the pulmonary artery mean larger blood volume of deoxygenated blood that will go to the lungs, and hence a larger volume of blood for oxygenation to take place?

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Which of the following factors will NOT influence the oxygenation of blood in the pulmonary circulation?
A. Rate and depth of breathing
B. Hemoglobin concentration of the blood
C.Blood pressure in the pulmonary artery
D. Surface area of the alveoli

for Choice C, think of it like this - pulmonary artery is deoxygenated blood. so by increasing the blood pressure, you are increasing the % of deoxygenated blood (meaning more CO2, less O2). I think the tricky part of this question is the wording. when they say "influences the oxygenation, i think they are hinting at promoting the oxygen content. Thus Choice C is clearly wrong.

Using process of elimination:

Rate and depth of breathing - TRUE; since faster breathing rate would case more co2 exhalation and more o2 inhalation; thus more O2 in blood.

Hemoglobin concentration - TRUE: more hemoglobin = more oxygen carrying capacity

Surface area of alveoli - TRUE; if there is mroe surface area available for oxygen absorbtion in the lungs, then more O2 would enter the body system, thus more o2 in the blood
 
for Choice C, think of it like this - pulmonary artery is deoxygenated blood. so by increasing the blood pressure, you are increasing the % of deoxygenated blood (meaning more CO2, less O2). I think the tricky part of this question is the wording. when they say "influences the oxygenation, i think they are hinting at promoting the oxygen content. Thus Choice C is clearly wrong.

Using process of elimination:

Rate and depth of breathing - TRUE; since faster breathing rate would case more co2 exhalation and more o2 inhalation; thus more O2 in blood.

Hemoglobin concentration - TRUE: more hemoglobin = more oxygen carrying capacity

Surface area of alveoli - TRUE; if there is mroe surface area available for oxygen absorbtion in the lungs, then more O2 would enter the body system, thus more o2 in the blood

Can someone explain why increasing blood pressure wouldn't increase bloood oxygenation?

Blood oxygenation is the amount of oxygen dissolved in the blood plasma right? So granted, increasing blood pressure is not the same as increasing the pressure above a solution, because that would cause more oxygen to dissolve into solution.

So do we see it as incresing blood pressure increases the amount of blood delivered? since the heart pumps harder.
Wouldn't that cause more blood to get to the lungs and more oxygen exchange to occur per second?

Trying to understand what exactly oxygenation entails
 
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