Buffers...

[cockblockandrun]

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From the 2010 ABA Gaps in knowledge report, this topic was one of the most commonly missed one:

Hemoglobin in the bloodstream possesses a greater buffering capacity than bicarbonate does.



Can someone explain this? I was under the impression bicarb was the best buffer but obviously according to the ABA, this is wrong...

 

[proman]

The bicarb system might be the most important but the hemoglobin system has the most capacity. Consider the amount of carbon dioxide produced every day (the major body acid-not organic acids), and the carbonic anhydrase system in RBCs. The histidines on Hgb readily accept protons in the deoxygenated state. Be sure to master the Haldane effect and carbonic anhydrase system, it's a board favorite.

 

[Idiopathic]

Heme binds H+ and releases O2 in acidic state and does the opposite in alkaline state. This is the fundamental point behind the oxygen-hemoglobin dissociation curve, and why you shouldnt give bicarb to someone with mild to moderate acidosis. 😉

If they tell you its the greatest capacity system, then thats what you should remember.

 

[lobelsteve]

Paging Dr. Bohr.

 

[DrMunkey]

Question #135 in Hall must be wrong/out of date. It still states that bicarb provides >=50% buffering capacity and Hgb ~35%. Is there new evidence in the last year showing Hemoglobin is the primary buffering system?

 

[Idiopathic]

maybe thats why its commonly missed