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Biochemistry

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Moderate

Bicarbonate Buffer System and Blood pH

BIOCHM-B6Q3XJ

The bicarbonate buffer system as shown in the reaction below is catalyzed by carbonic anhydrase and is extremely important in maintaining a stable blood pH through its control by respiration.

$${ CO }_{ 2 }{ +H }_{ 2 }{ O\rightleftarrows }{ H }_{ 2 }{ CO }_{ 3 }{ \rightleftarrows HCO }_{ 3 }^{ - }{ +H }^{ + }$$

Consider the equation above and determine ALL of the following statements which are NOT true regarding this buffering system.

A

The blood pH of a person experiencing hyperventilation (fast, deep breathing) would increase.

B

In blood, acid is best neutralized by carbonic acid (${ H }_{ 2 }{ CO }_{ 3 }$), whereas base is best neutralized by bicarbonate (${ H }{ C }{ O }_{ 3 }^{ - }$).

C

Carbonic acid is a strong acid and bicarbonate is a weak conjugate base.

D

One way to lower blood pH would be to repeatedly breathe into a bag.

E

The pH of blood is typically 7.4 and the ${ pK }_{ a }$ of carbonic acid is 6.1; therefore, there is more carbonic acid than bicarbonate present in the blood to maintain the pH.

F

Diarrhea can lead to a significant loss of ${ H }{ C }{ O }_{ 3 }^{ - }$ from the blood. This would result in acidosis.

G

If there is too little ${ H }{ C }{ O }_{ 3 }^{ - }$ in the blood, the kidneys can excrete ${ H }^{ + }$. This would cause a shift in the reaction equilibrium and increase ${ H }{ C }{ O }_{ 3 }^{ - }$ levels.