INTRODUCTION TO PATHOLOGY The study of -structural -biochemical & -functional changes in cells, tissues and organs that underlie the disease. By using morphological, microbiological, immunological and molecular techniques pathology provides basis for clinical care and therapy.

INTRODUCTION TO PATHOLOGY GENERAL PATHOLOGY - common reactions of cells and tissues to injurious stimuli. - reactions are non specific. SYSTEMIC PATHOLOGY - alterations and underlying mechanisms in organ specific diseases.

INTRODUCTION TO PATHOLOGY Four aspects of a disease process that form the core of pathology are ETIOLOGY (cause) PATHOGENESIS (biochemical and molecular mechanisms) MORPHOLOGICAL CHANGES (structural alteration in cells and organs) CLINICAL MENIFESTATIONS (signs and symptoms)

INTRODUCTION TO PATHOLOGY ETIOLOGY or CAUSE 1. GENETIC - inherited mutations - disease-associated gene variants & polymorphisms. 2. ACQUIRED - infections - nutritional - chemical - physical

INTRODUCTION TO PATHOLOGY PATHOGENESIS: Sequence of cellular, molecular and biochemical events that follow the exposure of cells or tissues to an injurious agent. - mutated genes - function of encoded proteins - biochemical events - morphological events - still not fully understood

INTRODUCTION TO PATHOLOGY MORPHOLOGICAL CHANGES: Structural alterations in cells or tissues - either characteristic of a disease or - diagnostic of an etiological process. MOLECULAR ANALYSIS: - To predict the behavior - for targeted therapy

INTRODUCTION TO PATHOLOGY FUNCTIONAL DERANGEMENTS and CLINICAL MANIFESTATIONS. Symptoms Signs Clinical course Outcome Clinicopathologic correlations

INTRODUCTION TO PATHOLOGY Rudolph Virchow in 19 th century CELLULAR BASIS OF DISEASE.

CELL INJURY Cellular Responses to Stress and Toxic Insults: ADAPTATION INJURY & DEATH

CELLULAR RESPONSES TO STRESS AND NOXIOUS STIMULI NORMAL CELL (homeostasis) ADAPTATIONS (reversible functional and structural responses to changes in physiological states and some pathologic stimuli) HYPERTROPHY HYPERPLASIA ATROPHY METAPLASIA

CELLULAR RESPONSES TO STRESS AND NOXIOUS STIMULI CELL INJURY REVERSIBLE INJURY ( mild, transient) IRREVERSIBLE INJURY (severe, progressive) CELL DEATH : 1. NECROSIS ( Denaturation of intracellular proteins and enzymatic digestion of lethally injured cell). 2. APOPTOSIS (Activation of intrinsic enzymes that degrade the cells, own nuclear DNA, nuclear and cytoplasmic proteins)

REVERSIBLE CELL INJURY CELLULAR SWELLING. ---Cells are incapable of maintaining ionic and fluid homeostasis. ---failure of energy-dependent ion pumps. ---hydropic change and vacuolar degeneration FATTY CHANGE. ---hypoxic injury ---toxic and metabolic injury ---lipid vacuoles in cytoplasm ---in hapatocytes and myocardium

REVERSIBLE CELL INJURY MORPHOLOGY: Cellular Swelling 1 st manifestation Pallor Torgor & Weight Vacuoles in cytoplasm ( Hydropic change or Vacuolar degeneration )

REVERSIBLE CELL INJURY ULTRASTRUCTURAL CHANGES OF REVERSIBLE CELL INJURY:- Plasma membrane alterations, blebbing, blunting, loss of microvilli. Mitochondrial changes. Dilatation of ER, seperation of ribosomes. Nuclear alterations, disaggregation of granular and fibrillar structures.

CAUSES OF CELL INJURY OXYGEN DEPRIVATION: Hypoxia, Ischemia. PYHSICAL AGENTS CHEMICAL AGENTS AND DRUGS INFECTIOUS AGENTS IMMUNOLOGIC REACTIONS GENETIC DERANGEMENTS NUTRITIONAL IMBALANCES