Biochemistry at The Biology Project

Clinical Correlates of pH Levels
Problem Set

Problem 3: Rapid response to mild acidosis

Tutorial to help answer this question

The bicarbonate buffering system of blood can respond quickly to mild metabolic acidosis (between pH 7.15 and 7.35) by:
A. expelling CO2 in the lung.
B. retaining HCO3- in the kidney.
C. excreting H+ in the kidney.
D. direct buffering action of the H2CO3 central intermediate.
E. retaining CO2 in the lung.


Bicarbonate buffering system & mild metabolic acidosis

The response to mild acidosis is actually a very complex process involving neural control of blood pressure and respiration rate. However, the most effective component of this response, the one that really rectifies the situation, is the expulsion of CO2 in the lung. The bicarbonate buffering system is best suited to deal with acidosis, in part because respiration expels CO2 and thereby diminishes H+.

In metabolically active tissues, such as muscle during intense exercise, production of CO2 (and acid, in the form of lactic acid) can lead to a transient fall in local pH.

The bicarbonate buffering system of blood can respond quickly to mild acidosis (between pH 7.15 and 7.35) by adjusting the CO2 release rate in the lungs. This adjustment can be made very rapidly--as anyone knows who has just climbed a steep flight of stairs!

[Problem 3] [Answer] [Problem 3]

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January 1999
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