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Oct11-10, 06:21 PM
P: 112
Mechanism for compensatory RESPIRATORY acidosis caused by metabolic alkalosis?

Metabolic alkalosis results in a depletion of blood H ions right - leaving blood pH higher than normal. Enzymes dont like the pH being off in the slightest - it affects their function - it affects the function of all proteins and all processes. Therefore there is a rapid way to get more H ions into the blood and correct pH. Slow breathing down - by reducing ventilation the partial pressure of CO2 builds up in blood - Co2 and water form bicarbonate and importantly for blood pH - a H ion. So now blood pH comes back down to normal pH. People generally consider the kidney when we talk of acid base control - but actually kidney takes hours to days to change function. the lungs by changinf ventilation can rapidly change blood ph. Slow ventilation - increase CO2 and acidify blood. Increase ventilation - blow off CO2 and reduced the H ion concentration.

All linked to

CO2 + H2O - H+ and HCO3-

by changing CO2 we drive the reaction forward or back. And hence compensate for any change in blood pH.