Pathophysiology or physiopathology is a convergence of pathology with physiology. Pathology is the medical discipline that describes conditions typically observed during a disease state, whereas physiology is the biological discipline that describes processes or mechanisms operating within an organism. Pathology describes the abnormal or undesired condition, whereupon pathophysiology seeks to explain the physiological processes or mechanisms whereby such condition develops and progresses.
Pathophysiology can also mean the functional changes associated with or resulting from disease or injury. Another definition is the functional changes that accompany a particular disease.