Chapter One Introduction to Pathology Section A DEFINITION OF PATHOLOGY
Definition of pathology Pathology is to study diseases by scientific methods Disease may be defined as an abnormal alteration of structure or function in any part of the body
Pathology focuses on 4 aspects of disease ETIOLOGY Cause of disease PATHOGENESI Mechanisms of development of disease MORPHOLOGY The structural alterations induced in celll and tissues FUNCTIONAL CONSEQUENCES Functional consequences of the morphologic changes, as observed clinically. Knowledge of etiology remains the backbones Disease diagnoses Understanding the nature of diseases Treatment of diseases
While much still needs to be uncovered to link abnormal genes and the expression of disease, gone are the time when the mechanisms of most diseases were unknown? or obscure? or mysterious?
One etiologic agent--one disease Several etiologic agents one disease. One etiologic agent--several diseases
Causes of cell injury and disease Oxygen deprivation( hypoxia, ischemia) Nutritional imbalances ● Physical agents Chemical agents and drugs ● Infectious agents Immunologic reactions ● Genetic derangements
HYPOXIA Ischemia( loss of blood supply ) Inadequate oxygenation cardiorespiratory failure ) Loss of oxygen-carrying capacity of the blood( anemia or Co poisoning )
HYPOXIC INJURY Loss of oxidative phosphorylation and AtP generation by mitochondria Decreased atP(with increase in AMP) stimulating fructokinase and phosphorylation, resulting in aerobic glycolysis. ° Depleted glycogen. Reduced intracellular pH: Lactic acid and inorganic phosphate Clumping of nuclear chromatin
Four biochemical themes Oxygen-derived free radicals. Loss of calcium homeostasis and increased intracellular calcium atP depletion. Defects in membrane permeability
PHYSICAL AGENTS rauma Heat Cold ● Radiation ● Electric shock