Consultant Medical Laboratory Scientist Assistant Professor of Histopathology & Cytopathology

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1 بسم اهلل الرحمن الرحيم By: PhD (Histopathology & Cytopathology), M.BA (Total Quality Management) Consultant Medical Laboratory Scientist Assistant Professor of Histopathology & Cytopathology

2 Introduction Pathology is the study of disease mechanisms. It is a discipline that bridge clinical practice and basic sciences, and it involves the investigation of the causes (aetiology) of diseases as well as the under lying mechanisms (pathogenesis) that result in the presenting signs and symptoms of the patients.

3 Introduction Pathology concern with the understanding the structural (morphology) and functional changes that occur in the cell, tissues, and organs so as to render diagnosis and guide therapy.

4 Introduction Traditionally pathology is divided into: general pathology and systemic pathology. General pathology: focuses on the fundamental cellular and tissue responses to pathologic stimuli, while Systemic pathology: examine the particular responses of specialized organs.

5 Causes of cell injury The causes of cell injury range from the gross physical trauma of a motor vehicle accident to the single gene defect that result in a defective enzyme underlying a specific metabolic disease. Most injurious stimuli can be grouped into the following categories:

6 Chemical Agents. Physical Agents. Infectious Agents. Genetic Defects. Aging. Nutritional Imbalances. Oxygen Deprivation.

7 Chemical Agents An enormous number of chemical substance can injure cell such as ; insecticides, CO, asbestos, ethanol. These substances can cause severe damage at the cellular level by altering membrane permeability.

8 Physical Agents Trauma, extreme of temperatures, radiations, electric shock, and sudden change in atmospheric pressure all have wide range affect on the cell.

9 Infectious Agents These range from sub-microscopic viruses to metre long tapeworm. These organisms can invade the human body and cause severe cell injury.

10 Genetic Defects Genetic defects can be conspicuous as the congenital malformations associated with Down syndrome or It may be subtle as the single amino acid substitution in haemoglobin S giving rise to sickle cell anaemia.

11 Aging Aging leads to alterations in replication and repair abilities of individual cell and tissues.

12 Nutritional imbalances Protein and calorie insufficiency, vitamins deficiency, and over excesses of nutrition s are also important causes of morbidity and mortality.

13 Oxygen Deprivation Hypoxia; oxygen deficiency, interferes with the aerobic oxidative respiration and is an extremely important and common cause of cell injury and death. Ischemia; is loss of blood supply in a tissue due to impeded arterial follow or reduced venous supply.

14 The morphology of cell and tissue injury (I). Reversible cell injury The two main morphologic correlates of reversible cell injury are cellular swelling and fatty changes. Cellular swelling: is the result of failure of energy-dependent ion pump in the plasma membrane, leading to an in ability to maintain ionic and fluid haemostasis.

15 The morphology of cell and tissue injury Fatty changes: occurs in hypoxic injury and various toxic or metabolic injuries, it is manifested by the appearance of small and large lipid vacuoles in the cytoplasm.

16 The morphology of cell and tissue injury (II). Irreversible cell injury Persistent or excessive injury causes cell to pass (THE POINT OF NO RETURN) into irreversible cell injury and death. Although there are no definitive morphologic or biochemical correlates of irreversibility, two phenomenas consistently characterise irreversibility;

17 The morphology of cell and tissue injury The inability to reverse mitochondrial dysfunction (lack of oxidative phosphorylation and ATP generation). Profound disturbances in membrane function.

18 The End

CELL INJURY. Severity of Cell Injury

CELL INJURY. Severity of Cell Injury GENERAL PATHOLOGY LECTURE - 3 DR. M. TARIQ JAVED Professor Department of Pathology, Faculty of Veterinary Science, University of Agriculture, Faisalabad, Pakistan. 9/11/2009 1 CELL INJURY No adaptive response