ABSTRACT
The pH of the extracellular fluid is maintained within narrow limits by a complex and incompletely understood control system. Arterial blood pH is stabilized between 7.39 and 7.41 indirectly through control of bicarbonate concentration ([HCO3
]) and carbon dioxide tension (PaCO2). The prevailing PaCO2 is itself in turn regulated by a tightly linked feedback system to pH through control of ventilation (see Chapter 3). The present chapter focuses on the regulation and maintenance of [HCO3
], where the control systems are less well defined.
