Diego Casali
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The P50 is defined as the partial pressure of oxygen (in mmHg) required to saturate half of the hemoglobin O2 binding sites in a sample of whole blood. In blood from a healthy adult, the P50 is approximately 26 mmHg when equilibrated with a mixture of 16% O2/5% CO2/79% N2. Which of the following manipulations will cause the P50 of the sample to increase?
A. Cooling the blood from 37°C to 20°C
B. Depleting its erythrocytes of 2,3-bisphophoglycerate
C. Equilibrating it with 16% O2/12% CO2/72% N2
D. Increasing its pH by 0.3 units using NaOH
E. Mixing it 1:1 with cord blood from a newborn
I think C is the correct answer, because an increase in pCO2 shifts to the right the O2 - binding curve.
A is not correct because a decrease in temperature shifts to the left the O2 - binding curve.
B is not correct because a decrease in 2,3-bisphosphoglycerate shifts to the left the O2-binding curve.
D is not correct because an increase in pH shifts to the left the O2-binding curve.
E is not correct because mixing the sample 1:1 with cord blood from a newborn will increase HbF concentration, thus left-shifting the O2-binding curve.
Do you agree with me?
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| Cedrick
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yes
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| robin082006
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C, this has been discussed
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| drpkaur
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YES C is correct because all other options will shift the curve towards left and by increasing pco2 will shift the curve towards right where p50 is raised in that situation..
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