q.5__________? - sarim

[ArchivalUser]

MBME 4 Q.


The P50 is defined as the partial pressure of oxygen (in mm Hg) 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 mm Hg 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 37C to 20 C
B. Depleting its erythrocytes of 2,3-bisphosphoglycerate
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

Plz Explain ur answer. thanks

[ArchivalUser]

CC
increase co2 concentration decrease the ph of the blood..
this shifts the ODC to right,,,
all other options mentioned here left shifts the ODC

[ArchivalUser]

DD Right shift curve?

[ArchivalUser]

CC NOT DD oops no can't be decrease in PH does this my mistake

[ArchivalUser]

C..

[ArchivalUser]

i think it is B. The P450 has to increase, that means the binding capacity of O2 has to increase.. this can happen with left shift of the curve.. pl correct me if i am wrong.

[ArchivalUser]

to increase p50,its right shift... so answer shud b a

[ArchivalUser]

CC

Increase in p50 means a right shift of the curve. Increased CO2 is the only choice given that will shift the curve to the right.
All other choices will cause a shift to the left.

Thank you for all Qs

[ArchivalUser]

CC is correct as explained above. Thanks

Cold Temperatures (A), Decreased 2,3 BPG (B), Alkalosis (D) and option E ------cz Left Shift of the curve (Dec P50)



Q- Do u know why "Mixing it 1:1 with cord blood from a newborn" will decrease P50 ?

[ArchivalUser]

This is because Hb F is made up of 2 alpha and 2 gamma subunits, which causes the Hb to have an increased binding of the O2.
It is a mechanism which enables O2 to be delivered from the maternal circulation, which has a higher O2 capacity through the placenta and to the fetal tissues. Fetal tissues have lower O2 concentrations.