BODY DEFENSE Specific vs Nonspecific Specific body defense

BODY DEFENSE

Specific vs Non-specific Specific body defense % pathogen limited 2% Non-specific body defense 98%

Non-specific 1 Lysosome in tear Barrier of skin Sebum of skin Gastric juice Acid in vagina

Barriers to entry are the skin and mucous membranes. The skin is a passive barrier to infectious agents such as bacteria and viruses. The organisms living on the skin surface are unable to penetrate the layers of dead skin at the surface. Tears and saliva secrete enzymes that breakdown bacterial cell walls. Skin glands secrete chemicals that retard the growth of bacteria. Mucus membranes lining the respiratory, digestive, urinary, and reproductive tracts secrete mucus that forms another barrier. Physical barriers are the first line of defense.

Non-specific 2 Phagocytosis by wbc

Non-specific 3 Complement element

Non-specific 4 Blood Clotting

When you cut yourself carelessly, why the wound stop bleeding after a while ? ? ? ∵Blood Clotting occurs: Platelets release a substance to turn soluble fibrinogen into insoluble fibrin which catches blood cells & seal off the cut

BLOOD CLOTTING is important because this can … Prevent the body from invasion of pathogens Stop excess bleeding (blood loss)

Inflammation The heat makes the environment When microorganisms penetrate unfavorable for microbes, skin or epithelium lining promotes healing, raises mobility white respiratory, digestive, or of urinary blood cells, and increases tracts, inflammation results. the metabolic raterelease of nearby cells. Damaged cells chemical Capillaries pass into interstitial signals such as fluid histamine that areas, causing the blood infected/injured increase capillary flow into area swell. area Clotting factors the to affected (causing thetrigger areas formation ofheated many small blood clots. to become and reddened). Finally, monocytes (a type of white blood cell) clean up dead microbes, cells, and debris.

Types of W. B. C.

Basophil The least common leucocyte; <1% of circulating white blood cells. Has a bilobed nucleus, often obscured by the numerous dense, basophilic (dark blue/purple) granules.

Monocyte Constitutes 2 -10% of leucocytes. Nucleus is large and indented, often with a horseshoe or bilolobed appearance. Cytoplasm is very pale and non-granular in appearance.

Neutrophil Most common type; constitutes 40 -75% of circulating leucocytes. Highly-lobulated nucleus (polymorphonuclear). Cytoplasm contains light purplish granules (large lysosomes).

Eosinophil Accounts for 1 -6% of circulating leucocytes. Characteristically a bilobed nucleus. Cytoplasm packed with large eosinophilic (dark pink; orange in this photo) granules.

Lymphocyte The smallest leucocyte. Makes up to 20 -45% of circulating white blood cells. Has a round, denselystained nucleus and a small amount of lightly-stained non-granular cytoplasm.

Specific immune responses w. Humoral w. Cellular

WBC action

Humoral immune response

B lymphocyte

Antibody formation

macrophage

Antibody

Action of antibody Burst pathogen Inactivate pathogen Detoxify toxic from pathogen Enhance macrophage

primary response secondary response antibody conc. immune response no immune response Time (days) first exposure to antigen X second exposure to antigen X

Cellular immune response

T lymphocyte

T- helper

Thymus

Action of cytotoxic T cell

Vaccine (Vaccination) Ï From dead / weakened pathogens – to stimulate the lymphocytes to produce antibodies Ï From injection of a serum Ï Times of injection: – first→ second → (booster) injection Ï It belongs to acquired immunity