Thursday, April 25, 2013

Acid Base 1

Acid Base 1

Kidney can acidify urine down to a pH of about 4.1.  This is not acid enough to get rid of the daily fixed acid load of about 80 mEq/day.  Therefore buffers are essential for survival.  Phosphate buffer is limited due to low plasma concentration.  Ammonium buffer is unlimited due to unlimited supply of glutamine.

Contraction alkalosis



K homeostasis



Handy Tools

Respiratory acidosis or alkalosis = rule of 12

acute:  if PCO2 is changed by 12, the pH should change by 0.1
e.g., PCO2 = 52, pH = 7.3
        PCO2 = 28, pH = 7.5

if pH does not follow this rule, there is compensation (needs days to happen)

Metabolic acidosis or alkalosis = rule of 6

acute:  if HCO3 is changed by 6, the pH should change by 0.1
e.g., HCO3 = 18, pH = 7.3
        HCO3 = 30, pH = 7.5

if pH does not follow this rule, there is compensation (needs seconds to happen)

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