Cellular defences

If an infections agent is not successfully repelled by the chemical and physical barriers than special type of cells involve in the encounter of foreign cells.
These cell are the part of innate immunity and whose number increases when any foreign particle enters.

1. CELLULAR DEFENCE

2. CELLULAR DEFENCE If an infections agent is not successfully repelled by the chemical and physical barriers than special type of cells involve in the encounter of foreign cells. These cell are the part of innate immunity and whose number increases when any foreign particle enters.

3. CELLS OF CELLULAR DEFENSE NEUTROPHILS CELLS MACROPHAGES CELLS N.K.C.(NATURAL KILLER CELLS)

4. 1.NEUTROPHILS CELL Neutrophils (also known as neutrocytes) are the most abundant type of granulocytes and the most abundant (40% to 70%) type of white blood cells in most mammals . They form an essential part of the innate immune system. They are formed from stem cells in the bone marrow . These cell have multilobe nucleus and their cytoplasmic granules is not stained by acidic or basic granules.

5. FUNCTION OF NEUTROPHILS They are the most important phagocytic cells. Neutrophils undergo a process called chemotaxis via amoeboid movement, which allows them to migrate toward sites of infection or inflammation . They are the cells which exhibits extravasation.

6. PHAGOCYTOSIS Neutrophils are phagocytes, capable of ingesting microorganisms or particles. For targets to be recognized, they must be coated in opsins a process known as antibody opsonisation.

7. EXTRAVASATION Leukocyte extravasation , less commonly called diapedesis , is the movement of leukocytes out of the circulatory system and towards the site of tissue damage or infection. This process forms part of the innate immune response.

8. 2.MACROPHAGES Macrophages are a type of white blood cell, of the immune system, that engulfs and digests cellular debris, foreign substances, microbes, cancer cells, and anything else that does not have the type of proteins specific to healthy body cells on its surface in a process called phagocytosis. These large phagocytes are found in essentially all tissues. They take various forms (with various names) throughout the body (e.g., histiocytic, Kuffer cells, alveolar macrophages, microglia, and others), but all are part of the mononuclear phagocyte system.

9. Cell Name Anatomical Location Adipose tissue macrophages Adipose tissue (fat) Monocytes Bone marrow/blood Kuffer cells Liver Sinus histiocytes Lymph nodes Alveolar macrophages (dust cells) Pulmonary alveoli of lungs Tissue macrophages (histiocytes ) leading to giant cells Connective tissue Microglia Central nervous system Hofbauer cells Placenta Intraglomerular mesangial cells Kidney Osteoclasts Bone

10. FUNCTION OF MACROPHAGES Macrophages are professional phagocytes and are highly specialized in removal of dying or dead cells and cellular debris. This role is important in chronic inflammation

11. 3. NATURAL KILLING CELLS Natural killer cells or NK cells are a type of cytotoxic lymphocyte critical to the innate immune system. The role NK cells play is analogous to that of cytotoxic T cells in the vertebrate adaptive immune response. NK cells provide rapid responses to viral-infected cells.

12. FUNCTION OF NK CELLS Catalytic granule mediated cell apoptosis :- NK cells are cytotoxic; small granules in their cytoplasm contain proteins, such as perforin and proteases known as granzymes. Upon release in close proximity to a cell slated for killing, perforin forms pores in the cell membrane of the target cell, creating an aqueous channel through which the granzymes and associated molecules can enter, inducing either apoptosis or osmotic cell lysis

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