Pathophysiology

Pathophysiology is the study of the functional changes that accompany disease and injury. It seeks to explain how and why normal physiological processes fail, and how these failures manifest as symptoms and signs. The field integrates concepts from physiology, pathology, biochemistry, and pharmacology to describe the cascade of events from molecular alterations to organ system dysfunction.

It distinguishes functional changes from structural abnormalities; while anatomy and pathology describe what tissue looks like, pathophysiology describes how function is altered. Researchers and clinicians analyze the causes (etiologies) of disease and the mechanisms (pathways) that drive progression, including genetic predisposition, infectious agents, autoimmune reactions, and environmental factors.

Core mechanisms include dysregulated signaling, inflammation, oxidative stress, metabolic derangements, and failures of homeostatic control. The body’s compensatory responses, such as hormonal activation or immune adaptation, may temporarily maintain function but can also contribute to disease progression. Pathophysiology connects laboratory findings to clinical presentation and treatment targets.

Examples illustrate its scope: in diabetes mellitus, insulin resistance and beta-cell dysfunction lead to hyperglycemia and vascular complications; in heart failure, reduced contractility triggers neurohormonal activation; in asthma, bronchial hyperresponsiveness and inflammation narrow airways; in chronic kidney disease, nephron loss alters filtration and fluid balance. This field underpins diagnosis, prognosis, and therapy.