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PATHOLOGY

PATHOLOGY . DR. NISREEN ABU SHAHIN ASSISTANT PROFESSOR OF PATHOLOGY FACULTY OF MEDICINE UNIVERSITY OF JORDAN. Pathology (PATHO- LOGY) is the study of diseases (pathos) = suffering (logos) = to study

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PATHOLOGY

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  1. PATHOLOGY DR. NISREEN ABU SHAHIN ASSISTANT PROFESSOR OF PATHOLOGY FACULTY OF MEDICINE UNIVERSITY OF JORDAN

  2. Pathology (PATHO- LOGY) is the study of diseases • (pathos) = suffering • (logos) = to study • Pathology deals with the structural and functional consequences of injurious stimuli on cells , tissues & organs ( etiology ,pathogenesis, morphology &the clinical significance) • Pathology includes general & systemic pathology

  3. Cell injury

  4. Causes of cellular injury 1- Hypoxia-ischemia: the most common cause a -Atherosclerosis and thrombi b -cardiopulmonary failure c -loss of oxygen carrying capacity: e.g. pneumonia, anemia , CO poisoning

  5. 2- Physical agents a -mechanical trauma b -extremes of tempretures c -sudden change in atmospheric pressure d -radiation e -electric shock

  6. 3 -chemical agents & drugs a-glucose & salts b-oxygen c-heavy metals d-insecticides e-ethanol f-carbon monoxide

  7. 4-infectious agent 5-immunologic reactions 6-genetic derangement 7-nutritional imbalance 8-aging

  8. Stages in the cellular response to stress and injurious stimuli

  9. Cellular adaptation to injury 1-physiologic Normal stimulation by hormones e.g. Enlargment of breasts in pregnancy & lactation 2-pathologic

  10. Cellular adaptation 1: Atrophy Shrinkage in the size of the cell due to loss of cell substance diminished function.

  11. Causes 1- Decrease workload 2- Loss of innervation 3- Decrease blood supply. 4- Inadequate nutrition. 5- Loss of endocrine stimulation 6- Aging

  12. Normal brain vs atrophic brain

  13. 2: Hypertrophy • It is an increase in the size of cells and consequently, an increase in the size of the organ. • More structural components. Types: 1- Physiologic: - uterus during pregnancy. - Muscle building. 2- Pathologic: - Cardiac hypertrophy in hypertension and - cardiac valve disease

  14. Cardiac muscle hypertrophy

  15. Cardiac hypertrophy involving theleft ventricle

  16. 3: Hyperplasia • It is an increase in the number of cells in an organ or tissue. • The increase in cell numbers means division of the cells • Note that not all types of tissues have this ability • Example: uterus during pregnancy

  17. 4- Metaplasia • is a reversible change in which one adult cell type (epithelial or mesenchymal) is replaced by another adult cell type. • The aim of this type of cellular adaptation: cells sensitive to a particular stress are replaced by other cell types better able to withstand the adverse environment. • Metaplasia is thought to arise by genetic "reprogramming" of stem cells rather than transdifferentiation of already differentiated cells.

  18. Examples: • 1- The squamous change that occurs in the respiratory epithelium in habitual cigarette smokers: The normal ciliated columnar epithelial cells of the trachea and bronchi are focally or widely replaced by stratified squamous epithelial cells. • 2- Chronic gastric reflux: the normal stratified squamous epithelium of the lower esophagus may undergo metaplastic transformation to gastric or intestinal-type columnar epithelium • 3- Bone is occasionally formed in soft tissues, particularly in foci of injury

  19. Cells are divided into 3 types depending on their ability to divide: 1-Cells with high capacity for Hyperplastic growth (labilecells): for example the epithelial cells that cover the skin and the mucus membranes and the inside surfaces of the organs; also the tissues that produce the different blood cells e.g hematopoietic cells in bone marrow ,epidermis, intestinal epithelium, exocrine duct epithelia,& transional epithelia of urinary bladder.

  20. 2-Cell with low capacity (permanentcells) e.g. Nerves and cardiac muscle cells. That is the reason why myocardial infarction or stroke leads to death of tissues in the heart and the brain

  21. 3-Cells with intermediate capacity (stablecells): e.g cartilage and smooth muscle.

  22. Hyperplasia can be divided into: 1. Physiologic: A. hormonal Hyperplasia (Breast, Uterus) B. Compensatory Hyperplasia (Liver) 2. Pathologic A. Excessive hormonal stimulation (endometrial hyperplasia) B. Effects of growth factors on target cells. - (Stimulation by growth factors, Wound healing, viral infection)

  23. Cell injury • cell injury results when cells are stressed so severely that they are no longer able to adapt or when cells are exposed to intrinsically damaging agents or suffer from intrinsic abnormalities.

  24. Types of cell injury • 1-reversible • 2-irreversible

  25. Reversible cell injury • In early stages or with mild forms of injury the functional and morphologic changes are reversible if the damaging stimulus is removed. • At this stage the injury has typically not progressed to severe membrane damage and nuclear dissolution

  26. Reversible Injury: 1-Cellular swelling 2-Fatty change.

  27. Cellular swelling • Microscopic examination may reveal small, clear vacuoles within the cytoplasm; these represent distended and pinched-off segments of the ER. This pattern of nonlethal injury is sometimes called hydropic change or vacuolar degeneration

  28. Fatty change -Abnormal accumulation of fat within parenchymal cell. - It occurs in cells participating in fat metabolism e.g hepatocytes and myocytes - manifested by the appearance of lipid vacuoles in the cytoplasm

  29. Cause of fatty change • Alcohol. • Malnutrition • Diabetes mellitus • Obesity • Hepatoxins • Chronic illnesses.

  30. The ultrastructural changes of reversible cell injury • include: • (1) plasma membrane alterations such as blebbing, blunting or distortion of microvilli, and loosening of intercellular attachments • (2) mitochondrial changes such as swelling and the appearance of phospholipid-rich amorphous densities • (3) dilation of the ER with detachment of ribosomes and dissociation of polysomes • (4) nuclear alterations, with clumping of chromatin

  31. Subcellular Alterations in Cell Injury: Effects of Injurious Agents on Organelles and Cellular Components • Some forms of cell injury affect particular organelles and have unique manifestations. • Autophagy: In nutrient-deprived cells, organelles are enclosed in vacuoles that fuse with lysosomes. In some cases indigestible pigment (e.g. lipofuscin) remains. • Hypertrophy of SER: Cells exposed to toxins that are metabolized in the SER show hypertrophy of the ER, a compensatory mechanism to maximize removal of the toxins. • Mitochondrialalterations: Changes in the number, size, and shape of mitochondria are seen in diverse adaptations and responses to chronic injury. • Cytoskeletalalterations: Some drugs and toxins interfere with the assembly and functions of cytoskeletal filaments or result in abnormal accumulations of filaments.

  32. A normal cell and the changes in reversible and irreversible cell injury (necrosis)

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