ABSTRACT
Homeostatic acid-base regulatory mechanisms aim to maintain a pH between 7.35 and 7.45 ([H+] of 45-35 nmol/L) via:
➤ buffers in tissue and blood ➤ excretion of acids by kidneys and lungs.
Normal acid-base balance relies on the following variables: ➤ pH ~ 7.40 ➤ PCO2 ~ 5.3 kPa (40 mmHg) ➤ HCO3-~ 25 mmol/L
An acid-base disturbance occurs when at least two of these three variables are abnormal. The primary change determines whether a disturbance is respiratory (alteration of PCO2)
or metabolic (alteration of the bicarbonate buffer system by means other than PCO2).
