General Pathology Lecture 1 PDF

Lecture - 1 – General pathology Dr. Ali Zaki Introduction : Pathology is a Greek word composed of two parts, " pathos" mean suffering , and " logos" mean study, so the pathology is the science that study structural and functional changes occur in...

Lecture - 1 – General pathology Dr. Ali Zaki Introduction : Pathology is a Greek word composed of two parts, " pathos" mean suffering , and " logos" mean study, so the pathology is the science that study structural and functional changes occur in cells, tissues, and organ that are expressed as diseases. Pathology includes the following branches : 1- Anatomical surgical pathology: study diseases from the structural abnormalities of the cells and tissues ( autopsy and biopsy) 2- Clinical pathology: A- Hematology: study diseases of the blood, as well as effects of other disease on the blood. B- Chemical pathology: study the disease from perspective of biochemical abnormalities. C- Immunology: study primary diseases of immune system, as well as the effects of other diseases on the immune system. D- Microbiology: study infectious diseases. E- Genetics : study genetic disorders Studying of pathology can be divided into two main parts: 1- general pathology: this part focus on the mechanisms of the principal types of disease process. (inflammation , degeneration, tumors). 2- systemic pathology: this part examines the effects of specific diseases on specialized organs.(appendicitis, lung cancer,..). Disease: It’s the clinical manifestation, through signs and symptoms, of underlying abnormality. The abnormality may be structural or functional or both. The characteristics of disease: 1- etiology: the cause of the disease whether congenital or acquired. 2- pathogenesis: mechanism or serial steps of disease process. 3- manifestations: morphological and functional changes. 4- complications: secondary effects of a particular disease. 5- prognosis: out come of the disease(good to bad). 6- epidemiology: incidence of the disease. Homeostasis: Normal steady state of the cell in which the cell handle normal physiological demands. Cell adaptation: It’s a new altered steady state in which cell preserve viability, but modulate its morphology and function in response to physical stress or pathological stimuli. Types of adaptive responses of the cell: 1- Cell atrophy: shrinkage in size of the cell by the loss of cell substance; and when sufficient number of cells are involved, the entire tissue or organ diminishes in size and becoming atrophied. Causes of cell atrophy:  Immobilization " fracture".  Loose of innervation " poliomyelitis".  Diminished blood supply " ischemia".  Inadequate nutrition "starvation".  Lose of endocrine stimuli " uterus after menopause".  Aging " brain atrophy" Mechanism of atrophy: Reduction of cellular component underlying by the followings:  Decrease synthesis.  Increase catabolism.  Both of the above. 2- Cell Hypertrophy: Increase in the size of the cells and consequently an increase in the size of an organ, this increase is due to increase synthesis of structural proteins and organelles. Types of hypertrophy: A- Physiological hypertrophy : as a normal physiological response like increase muscle mass due to work overload on skeletal muscles seen in weight lifter and body builder. B- Pathological hypertrophy " ex. left ventricular hypertrophy in patient with hypertension or heart valve stenosis, Since the cardiac muscle push blood through stenosis of cardiac valve and face much more resistance than in normal heart valve. Another example is enlargement of viable cardiac muscle after Myocardial Infarction to compensate for the death of neighboring cell die due to ischemia. Mechanism of cell hypertrophy : Activation of cell receptors, genes, and growth factors that lead to increased synthesis of protein and cell organelles. 3- Cell Hyperplasia: Increase in number of cells. Types of hypertrophy: A- Physiological hyperplasia : 1- Hormonal " proliferation of breast lobules in lactating female. 2- Compensatory " when part of tissue removed or diseased like in liver partial resection, and connective tissue cells in wound healing, the neighboring healthy cells proliferate and increased in number. B- Pathological hyperplasia: Its mainly due to hormonal access or growth factor stimuli.  Endometrial hyperplasia due to progesterone-estrogen imbalance, this hyperplasia presenting as abnormal uterine bleeding.  Benign prostatic hyperplasia 'BPH' in elderly males presenting as urine retention. Mechanism of cell hyperplasia Hyperplasia is the result of growth factor–driven proliferation of mature cells and, in some cases, by increased output of new cells from tissue stem cells. 4- Cell Metaplasia: Its reversible change in which a type of epithelial or mesenchymal cell is replaced by another adult cell type, so it’s a cellular adaptation where by cell sensitive to a particular stress are replaced by other cell type able to withstand the adverse environment. Usual site for Metaplasia are: ( a ) squamous metaplasia occur in respiratory epithelium of cigarette smokers, so the normal ciliated columnar epithelial cells of the trachea and bronchi are replaced by stratified squamous epithelial cells, although the squamous cells have survival advantage of respiratory cells, the important protective mechanism are lost such as mucous secretion and ciliary movements.  ( b ) barrette esophagus in which normally present stratified squamous epithelial cells of the lower esophagus replaced by gastric or intestinal type of columnar epithelium, this metaplasia is usually seen in prolonged or chronic reflux esophagitis. Mechanism of metaplasia: Metaplasia does not result from a change in the phenotype of an already differentiated cell type; instead it is the result of a “reprogramming of stem cells exist in normal tissues, or of undifferentiated mesenchymal cells present in connective tissue”. Disadvantages of metaplasia : 1- lose the function of cells. 2- If influences that induce metaplastic transformation persist, it may induce cancer transformation.