General Pathology

DIPHTHERIA An acute, contagious disease caused by Corynebacterium diphtheriae, characterized by the formation of a fibrinous pseudomembrane, usually on the respiratory mucosa, and by myocardial and neural tissue damage secondary to an exotoxin. Cutaneous diphtheria (infection of the skin) can occur when any disruption of the integument is colonized by C. diphtheriae. Lacerations, abrasions, ulcers, burns, and other wounds are potential reservoirs of the organ…

THROMBOSIS  Pathogenesis (called Virchow's triad): 1. Endothelial* Injury ( Heart, Arteries) 2. Stasis 3. Blood Hypercoagulability - Endothelial cells are special type of cells that cover the inside surface of blood vessels and heart. CONTRIBUTION OF ENDOTHELIAL CELLS TO COAGULATION Intact endothelial cells maintain liquid blood flow by:  1- inhibiting platelet adherence 2- preventing coagulation factor activation 3- lysing blood clot…

INFARCTION  An infarct is an area of ischemic necrosis caused by occlusion of either the arterial supply or the venous drainage in a particular tissue   Nearly 99% of all infarcts result from thrombotic or embolic events    other mechanisms include: local vasospasm, expansion of an atheroma, extrinsic compression of a vessel (e.g., by tumor); vessel twisting (e.g., in testicular torsion or bowel volvulus; and traumatic vessel rupture…

POLYCYTHEMIA  It is an increase in number of RC per unit volume of blood (Hb more than 1.9.5 gms% and 18 gms% for women)   Causes : True polycythemia. - Idiopathic Polythemia vera. - Secondary to :     o    Hypoxia of high altitude , heart disease, chronic lung disease etc.     o    Erythopoietin  oversecretion as in renal diseases , tumours of liver, kidney and adrenal etc. …

Thalassaemia. Genetic based defect in synthesis of one of the normal chains. Beta thalassaemia --->  reduced Hb A and increased HbF (α2, Y2) HBA2(α2) Alpha thalassaemia  --->   reduced  Hb-A, Hb-A2 and Hb-F-with formation of Hb-H(β4) and Hb Barts (Y4). Thalassaemia may manifest as trait or disease or with intermediate manifestation. Features: •    Microcytic hypochromic RBC is in iron deficjen…