The first in this two-part article explores the short-term homeostatic mechanisms involved in maintaining the ‘acid-base balance’ of body fluids. The second article identifies the intermediate and long-term homeostatic mechanisms involved in maintaining the ‘acid-base balance’. The acid-base balance of the body refers to the ideal pH of body fluids, which is determined by the hydrogen ion (H+) concentration of body fluids. Normal pH optimizes enzyme action and a healthy metabolism. Prolonged abnormal pH leads to disordered metabolism and illness, therefore, an understanding of pH is crucial for nurses who have access to patient’s medical records. Since observing a patient’s blood and urine pH aids assessment, diagnostics, planning care, implementing care and re-evaluating healthcare intervention. The aim of this article is to educate nurses in the understanding of the biochemical functioning of buffers as the short-term regulators of pH control.