Biology of Disease

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DISORDERS OF

ACID–BASE BALANCE

9.1 Introduction

The concentration of hydrogen ions, H+, in the blood is kept within a narrow
reference range to give the blood a pH of approximately 7.4. The body
possesses physiological and biochemical mechanisms that maintain this pH by
removing excess H+ and carbon dioxide produced during metabolism (Figure
9.1). These activities are vital for normal bodily functions and are performed
by the renal and respiratory systems respectively. Failure to maintain the

Diet Metabolism Excretion

Protein

Fats

Carbohydrate

CO 2

Lactic acid

Ketoacids

pH

7.35 to 7.45

H+ Kidneys

CO 2 Lungs

Blood

Figure 9.1 Overview of the production, transport

and excretion of CO 2 and H^.

OBJECTIVES

After studying this chapter you should be able to:

N describe how hydrogen ions are transported by the blood;

N outline the role and operations of the blood buffering systems;

N calculate the concentrations of ingredients used to prepare buffered

solutions of defined pH and concentration;

N explain the role of kidney tubule cells in excreting hydrogen ions and regen-

erating plasma hydrogen carbonate;

N explain the causes of disorders of acid–base balance;

N describe the strategies for investigating disorders of acid–base balance;

N outline the management of disorders of acid–base balance.