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Microbiology immune system, antibiotics, immunity


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The physical barriers for infection. (1st line of defesnse)
Skin, mucous membranes, normal flora.
What is the 2nd line of defense?
Phagocytosis, inflammation, fever, and antimicrobial substances.
What is the inflammation process?
pain, heat, redness (erythema) swelling (edema). Area is scratched histamine is released, which causes vasodilation, sending in phagocytes (nuetrophiles)to kill the invading microbe. This helps also to limit the effects of the microbe on the body and repair tissue.
4 Mechanisms of Phagocytosis.
Chemotaxis: chemical attraction of phagocytes to microorganisms. WBC, damaged tissue, and microbial products.
Adherence: the phagocyte attaches to the microbe
ingestion: psuedopodssurround microbe, it is taken into the phagocyte as a phagosome.
Digestion: lysosome combines with phagosome to create a phagolysosome-this releases lysozome which hydrolyses peptiodoglycan in bacterial cells.
The complement sytem
A series of proteins that are produced by the liver. They are used as a cascade and can trigger the proteins to aid in cytolysis, phagocytosis and inflammation. When split the become C3- C3a C3b.
This helps with phagocytosis because C3 protein breaks into 2 C3a and C3b, and C3b binds ot the surface of an invading microbe. This covers the whole microbe and receptors on the phagocyte attach to this much easier than just ingesting it.
Classic Pathway
1) pair of antibody molecules attach to an antigen. Antibody antigen complex. This activates C1. 2)C1 activates C4 and C2 by splitting them.
3) C4b and C2b combine and activate C3 which aids in inflammation, opsinization, and cystolysis.
Alternative Pathway
C3 combines with B factor, D factor and P factor on the surface of an antigen. Other complement proteins are attrachted to the surface of microbial cells, and when this happens C3 is activated into C3a, which helps in inflammation and C3b which helps in oppsinization and cystolysis.
Lectin Pathway
Lectins are produced by the liver and phagocytes stimulate them to be released. (lectins are proteins that bind to carbs.) 1) Mannose binding lectin binds to mannose which is found in bacterial cell walls. MBL acts as a opsonin to enhance phagocytosis.
2) this activates C2 and C4
3) C2 C4 activate C3. and on and on.
a class of similar antiviral proteins produced by certain animal cells after viral stimulation. On function of interferons is to interfere with viral multiplication.
Naturally acquired immunity
Active: Having a sickness and then building up the antibodies against it.
Passive: Antibodies are passed from the mother to the fetus via placenta or to infant in the mother's milk.
Artifically acquired immunity
Active: Antigens are introduced in the body by vaccines.
Passive: Performed antibodies in immune serum are injected into body. (immunoglobulin)
The study of the interaction between antibodies and antigens.
Humoral immunity (antibody medicated immunity)
Involves the production of antibodies that act against foreign organisms and substances. Found in plasma, lymph, mucus secretion. B cells are part of humoral immunity and produce antibodies. Mainly effective against bacteri, bacterial toxins and viruses circulating in the blood.
Cell mediated immunity
involved speacilized lymphocytes (T cells) that act against forgein organisms or tissue. T cell regulate the proliferation of other immune cells like macrophages. Cell mediated works well against bacteria and viruses located within phagocytes. Also against fungi, protozoa, and worms. Also forgein transplanted tissue.
Most are either proteins or large polysaccharides that reside on the cell wall of a bacterial cell.
These are proteins (immunoglobulins) that are made in response to invation of the body by antigens. Antibodies are usually monomers which have a stema and then two prods, making the shape of a Y.
Immunoglobulin classes

IgG: 80% of all antibodies in serum. This readlit crosses the walls of blood vessels and enter tissue fluid. This is the antibody that crosses the placenta to the child. This Ig protects against circulating bacteria and viruses.
These make up about 5-10%

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