The Power Course

Normal pH of arterial blood is


1 ) 7.35 to 7.45
2 ) 7.30 to 7.50
3 ) 7.30 to 7.40
4 ) 7.40 to 7.50


pH of blood is tightly controlled. Arterial blood pH is 7.40. Venous blood pH is slightly less than arterial blood. Acidosis is technically present if the pH is less than 7.4 and alkalosis more than 7.4. But, the ill effect of acidosis does not occur until pH falls below 7.35 and for alkalosis more than 7.45.

Types of acid-base disorders

Disorder pH 7.35 to 7.45 Bicarbonate HCO324.1mEq/L Carbon Dioxide PCO40mmhg
Metabolic Acidosis Decreased Decreased Decreased
Metabolic Alkalosis  Increased Increased Increased
Respiratory Acidosis Decreased Increased Increased
Respiratory Alkalosis Increased Decreased Decreased

CO2 H2O ⇌ H2CO3 ⇌ H+ + HCO3-

Respiratory Acidosis

pH is decreased due to an increase in CO2 levels this leads to compensation. when more carbon dioxide is present more carbonic acid is produced and this increases the Hydrogen ions thus acidosis and bicarbonate levels also go up. see the equation above Shift to right. Kidney retains bicornate ions



Type 2 Respiratory failure

Breathing CO2 more than 7%

Respiratory Alkalosis

pH is increased due to the elimination of CO2 (hyperventilation), this leads to compensation see the equation below. when CO2 is reduced less carbonic acid is produced leading to fewer hydrogen ions and also fewer bicarbonate ions shift to left. Kidneys excrete bicornate ions


Voluntary hyperventilation

Three-week residence at 4000 m altitude

Metabolic Acidosis

pH is decreased with the fall of bicarbonate this leads compensation from lungs i.e hyperventilation so more CO2 is eliminated thus even CO2 gets decreased.


Diabetic acidosis

Renal Failure

NH4CL ingestion

Metabolic Alkalosis

pH is increased due to an increase in bicarbonate levels. This leads to the companization i.e. retention of CO2 by lungs so CO2 levels go up


NH4CO3 ingestion

Excessive Vomiting


7.35 to 7.45

Last Modified : 25-Dec-2019

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