Osler expresses particularly well the relation between the basic sciences
and clinical medicine in the aphorism cited above. Indeed, ever
since the Middle Ages, wise physicians and others concerned with
the sick and their care have realized that most human disease may
be understood in a real sense as disordered physiology (pathophysiology).
Something (eg, a mutation in a gene or invasion by a bacterial organism)
triggers an illness, and the body reacts with molecular, cellular,
and systemic responses that are the symptoms and signs of the disease.
Therefore, with proper knowledge of normal structure and function, and
the ways in which these can become disordered, comes the ability
to understand disease and to design rational and effective treatment.
In addition, of course, the relation between pathophysiology and
disease is a two-way street. Diseases may be viewed as “experiments
of nature” that may uncover previously unknown or unappreciated
physiologic mechanisms, and the investigation of these physiologic
mechanisms in normal individuals advances our fundamental biomedical
knowledge. Therefore, it is important that students understand normal
structure and function, and how they can become disordered, and
apply this knowledge to disease.