4. necrosis in details. apoptosis also .

necrosis is defined as unprogammed death of cells in the body. due to infection, cancers , serious injury ., presence of venom, severe inflammation and variety of diseases.

1. NECROSIS

2. Necrosis Necrosis = Death / premature death of cells in living tissue. In necrosis, excess fluid enters the cell, swells it, & ruptures its membrane which kills it. After the cell has died, intracellular degradative reactions occur within a living organism. Narcosis???

3. In an average adult human, between 50 billion and 70 billion cells die off and are replaced every day, but necrosis refers to cell death that is unprogrammed and results from atypical body conditions, such as infections, cancer, serious injury, the presence of venom, severe inflammation , and a variety of diseases.

4. How it happens ?? I N F L A M M A T I O N

5. Necrosis does not occur in dead organisms. In dead organisms, autolysis & heterolysis take place

6. The brown recluse spider, whose bite can cause necrotic lesions up to 10 inches (25 centimeters) in diameter. Loxoscelism

7. Morphology changes Necrotic cells show increased eosinophilia. H ave a more glassy homogeneous appearance than do normal cells, mainly as a result of the loss of glycogen particles. the cytoplasm becomes vacuolated and appears moth-eaten . Dead cells may be replaced by large, myelin figures . the dead cells may ultimately become calcified.

8. Types of necrosis The types of necrosis include: 1. Coagulative necrosis 2. Liquefactive necrosis 3. Fat necrosis 4. Caseous necrosis 5. Gangrenous necrosis

9. Morphological patterns of Necrosis Coagulative necrosis is a type of accidental cell death typically caused by ischemia or infarction . In coagulative necrosis the architecture of dead tissue is preserved for at least a couple of days. A localized area of coagulative necrosis is called an infarct

10. Liquefactive necrosis Liquefactive necrosis (or colliquative necrosis ) is a type of necrosis which results in a transformation of the tissue into a liquid viscous mass.. It is seen in focal bacterial or, occasionally, fungal infections. The necrotic material is frequently creamy yellow because of the presence of dead leukocytes and is called pus . For unknown reasons, hypoxic death of cells within the central nervous system often manifests as liquefactive necrosis

11. Gangrenous necrosis It is usually applied to a limb, generally the lower leg, that has lost its blood supply and has undergone necrosis (typically coagulative necrosis) When bacterial infection is superimposed there is more liquefactive necrosis because of the actions of degradative enzymes in the bacteria and the attracted leukocytes (giving rise to so-called wet gangrene ).

12. Nuclear changes Karyolysis  a change that presumably reflects loss of DNA because of enzymatic degradation by endonucleases Pyknosis  characterized by nuclear shrinkage and increased basophilia . the chromatin condenses into a solid,shrunken basophilic mass. Karyorrhexis  the pyknotic nucleus undergoes fragmentation.

13. Apoptosis It is type of cell death which helps to eliminate unwanted cells--an internally SUICIDE PROGRAM series of events effected by dedicated gene products Apoptosis is the death of single cells within clusters of other cells.

14. Apoptotic cells break up into fragments, called apoptotic bodies , which contain portions of the cytoplasm and nucleus . The plasma membrane of the apoptotic cell and bodies remains intact, but its structure is altered in such a way that these become “tasty” targets for phagocytes.

15. When a cell is compelled to commit suicide , proteins called caspases go into action. They break down the cellular components needed for survival.

16. Apoptosis is not followed by inflammation or calcification. Examples: The resorption of the tadpole tail at the time of its metamorphosis into a frog occurs by apoptosis. The formation of the fingers and toes of the fetus requires the removal, by apoptosis, of the tissue between them. The sloughing off of the inner lining of the uterus (the endometrium) at the start of menstruation occurs by apoptosis

17. CAUSES OF APOPTOSIS Apoptosis occurs normally both during development and throughout adulthood, and serves to eliminate unwanted, aged or potentially harmful cells. It is also a pathologic event when diseased cells become damaged beyond repair and are eliminated.

18. Apoptosis in Physiologic Situations During development for removal of excess cells during embryogenesis To maintain cell population in tissues with high turnover of cells, such as skin, bowels. Hormone-dependent involution - Endometrium, ovary, breasts etc . Elimination of potentially harmful self reactive lymphocytes.

19. To remove damaged cells by virus To eliminate cells with DNA damage by radiation, cytotoxic agents etc. Cell death in tumours Apoptosis in Pathologic Situations

20. In summary , cell Death:- cell death Necrosis Types. M&N changes Apoptosis P&P situation Features.

21. Autophagy Autophagy is a process in which a cell eats its own contents. It is a survival mechanism in times of nutrient deprivation. In this process intracellular organelles and portions of cytosol are first sequestered from the cytoplasm in an autophagic vacuole, which subsequently fuses with lysosomes to form an autophagolysosome , and the cellular components are digested by lysosomal enzymes

22. Intracellular Accumulations DEFINITION : Accumulation of abnormal amounts of various substances due to manifestations of metabolic derangements in the cell.

23. TYPES OF ACCUMULATIONS :There are 2 basic types of accumulations: 1. Excess of substances normal to the particular cell. 2. Abnormal substances in three mechanisms: - (a) decrease in normal metabolic removal. - (b) inability to metabolize the substance. - (c) deposition of abnormal exogenous substance in which the cell has no mechanism to metabolize it.

24. CATEGORIES : 1. Normal cellular constituents e.g ., water, lipids, CHO. 2. Abnormal substances a ) Exogenous  Substance accumulate because the cell can neither degrade the substance nor the ability to transport it to other sites. e.g., mineral or products of infectious agents

25. Exogenous Accumulations Pneumoconioses - or dust diseases: Anthracosis - coal dust Silicosis-silica dust inhalation in stone workers, sandblasters, miners Siderosis - iron dust Asbestosis- blue, brown, red asbestos and crosidolite in shipbuilding workers, insulation and electrical work Plumbism -lead accumulation Byssinosis -cotton fibers Phytopneumoconiosis - plants or vegetables’ pollen,etc .

26. b) Endogenous  Substance that cannot be metabolized because of deficiency or defect of the enzyme and accumulate in cells. e.g., products of abnormal synthesis or metabolism

27. CHLOASMA  Tan or brown pigmentation commonly associated with pregnancy or the use of oral contraceptives . Also called the mask of pregnancy or melasma .

28. Steatosis ( Fatty Changes) The terms steatosis and fatty change describe abnormal accumulations of triglycerides within parenchymal cells.

29. Organs Involved & Causes Fatty change is often seen in the liver because it is the major organ involved in fat metabolism, but it also occurs in heart, muscle, and kidney. Disorder with heoatocyte damage. The causes of steatosis include toxins, protein malnutrition, alcohol and anoxia Disorder with Hyperlipidemia. diabetes mellitus and obesity.

30. Assignment. proteins, Glycogen, Pigments ,Hyaline Change Endogenous and Exogenous Constituents

31. THANK YOU