carbonic anhydrase inhibitor

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hacheemaster

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The following question is from EK bio review, chapter 7, question 154.

Which of the following would most likely occur in the presence of a carbonic anhydrase inhibitor?
A. The blood pH would increase.
B. The carbamino hemoglobin concentration inside erythrocytes would decrease.
C. The rate of gas exchange in the lungs would decrease
D. The oxy hemoglobin concentration inside erythrocytes would increase.


Carbonic anyhydrase catalyzes the following reaction: CO2 + H20 <=>H+ + HCO3-. I put down B because I thought the relative concentration of bicarbonate ion would decrease, which means there would be less bicarbonate ion going into hemoglobin to form carbamino hemoglobin. Therefore, we the carbamino hemoglobin concentration inside erythrocytes wuold decrease.

A is wrong because pH would decrease in the tissues if we have less reduced hemoglobin to buffer the blood, while increasing in the lungs because of H+ being bound to hemoglobin.

The correct answer is C...I guess I see that there would be less partial pressure of CO2 in the blood relative to the alveolus/air and that means decreased transfer of gas particles, but why is C more correct than B?

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I would say that CO2 is transported as a carbamino-hemoglobin complex or as bicarbonate.

If there is no bicarbonate, since it cannot be formed, than more of the CO2 would have to be transfered as the hemoglobin complex, and thus its concentration would increase.

EDIT - Your thinking is correct, but bicarbonate doesn't bind with hemoglobin, CO2 does.
 
ohhhhhhhhhh. That makes sense! I just want to make sure of one last thing. CO2+hemoglobin=carbamino-hemoglobin=carboxyhemoglobin, while bicarbonate simply enters the erythrocyte without binding to hemoglobin. Correct?
 
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ohhhhhhhhhh. That makes sense! I just want to make sure of one last thing. CO2+hemoglobin=carbamino-hemoglobin=carboxyhemoglobin, while bicarbonate simply enters the erythrocyte without binding to hemoglobin. Correct?

Ummm H+ and Bicarbonate are hydrophilic, they shouldn't have to bind anything they can just dissolve in the blood.
 
Oxygen exchange in the lungs is due to Low CO2 and High PH to shift the hemoglobin dissociation curve to the left.

If you have a lower PH in the lung you are not going to bind Oxygen as well because you stabilize the tense state. I guess you would have more H+ in the lungs because you cant convert it back to CO2.

Lower PH in the lungs would make the gas exchange rate decrease.

Is this reasoning logical? I don't know if its the right answer.
 
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