 Definition ◦ It is combination of two Latin words ◦ Pathos meaning disease ◦ Logos meaning study Pathology is a branch of medicine that deals with the nature of disease. the study of the structural, biochemical, and functional changes in cells, tissues, and organs that underlie disease

 General pathology ◦ reactions of cells and tissues to abnormal stimuli  Systemic pathology ◦ alterations in specialized organs and tissues that are responsible for disorders that involve these organs

 Etiology (cause)  Pathogenesis (mechanisms of its development )  Molecular and morphologic changes (biochemical and structural alterations induced in the cells and organs of the body)  Clinical manifestations (functional consequences of these changes)

 Basic Molecular Biology  Basic Pathology*  Principles and practice of molecular pathology*  Molecular Biology of the Cell  Concepts in molecular biology  Concepts in genetics  Understanding molecular pathogenesis*  Clinical pathology*  Introduction to Bio-Informatics  Applied Comparative Pathology*

 Clinical proteomics and molecular pathology*  Integration of molecular and cellular pathogenesis*  Molecular pathology of human diseases*  Molecular basis of diseases of pathology of immunity*  Infection and host response*  Molecular mechanism of cell death*

 Modern Drug Discovery Technologies  Practical Histopathology and Mouse Models of Human Disease  Microbial pathogenesis*  Modern Methods in Molecular Pathology*  Molecular Pathology of Cancer*  Biological Therapies  Molecular diagnosis of Infection  The human epigenome

 DNA Extraction RNA extraction  Blood group Test  Blood Sugar test  PAGE  Histopathology  ELISA  Immuno Histochemistry

Nature of Injurious StimulusCellular Response ALTERED PHYSIOLOGICAL STIMULI; SOME NONLETHAL INJURIOUS STIMULI Increased demand, increased stimulation (e.g., by growth factors, hormones) Decreased nutrients, decreased stimulation Chronic irritation (physical or chemical) CELLULAR ADAPTATIONS Hyperplasia, hypertrophy Atrophy Metaplasia REDUCED OXYGEN SUPPLY; CHEMICAL INJURY; MICROBIAL INFECTION Acute and transient Progressive and severe (including DNA damage) CELL INJURY Acute reversible injury Cellular swelling fatty change Irreversible injury ➙ cell death Necrosis Apoptosis

Nature of Injurious StimulusCellular Response Metabolic Alterations, Genetic OR Acquired; CHRONIC INJURY Intracellular Accumulations; CALCIFICATION Cumulative Sublethal Injury over long life span CELLULAR AGING

 Hypertrophy refers to an increase in the size of cells, resulting in an increase in the size of the organ.  Synthesis of more structural proteins  May be physiological ◦ Breast and uterus ◦ LVH ◦ Skeletal muscle  Pathological ◦ Uterus under influence of estrogen secreted by ovarian cancer

 Vascular supply  Diminished oxidative capability of the mitochondria  Altered protein synthesis and degradation

 Hyperplasia is an increase in the number of cells in an organor tissue, usually resulting in increased volume of the organ or tissue. ◦ Hormonal (breast, uterine muscles) ◦ Tissue loss (kidney, liver) Mechanism of hyperplaia is by mitotic division

Normal myocyte Hypertrophied myocyte Adaptation Reversible cell injury Cell death

 Atrophy is reduced size of an organ or tissue resulting from a decrease in cell size and number  Physiological ◦ Decreased workload ◦ Inadequate nutrition ◦ Aging  Pathological ◦ Loss of innervation ◦ Loss of endocrine stimulation ◦ Diminished blood supply

 Increased degradation or decreased synthesis of cellular proteins  Hormones (insulin, thyroid hormones, glucodorticoids and prostaglandins) Examples of atrophy  Thymus atrophy  Gonadal atrophy with age  Starvation  Disuse atrophy  Denervation  Diminished blood supply  Pressure

 Metaplasia is a reversible change in which one differentiated cell type (epithelial or mesenchymal) is replaced by another cell type  an adaptive substitution of cells that are sensitive to stress by cell types better able to withstand the adverse environment

 Chronic irritation  Chronic inflammation  Vit A deficiency  Examples  Epithelial metaplasia ◦ Columnar to squamous metaplasia (trachea, bronchi). ◦ Atypical metaplasia.