On Thursday, May 9, 2013
Nonspecific immunity is when components eliminate pathogens before they can cause disease.
Specific immunity is when components adapt to new diseases (by creating memory cells) and their main role becomes to attack a certain kind of pathogen.
NONSPECIFIC DEFENSE MECHANISMS:
A). Skin and Mucus membranesSkin is an impenetrable barrier to viruses and bacteria if it is not broken.
It is reinforced by chemical defenses. Oil and sweat give the skin a pH of 3-5.
Bacteria that live on the skin help by releasing acids and wastes to kill off unwanted microorganisms. Lysozyme is found in tears and saliva which can destroy the cell walls of most bacteria. Gastric juices kill off bacteria in food. Mucus captures bacteria in the nose and throat cavities of the body.
B). Phagocytes and Natural Killer Cells
Phagocyte are cells that eat other cells or objects found in the body.
Macrophages a type of phagocyte that eats bacteria, viruses, and the debris of damaged cells. They develop from a class of white blood cells called MONOCYTES. Neutrophils are another type of white blood cell capable of becoming phagocytotic.
Natural Killer Cells destroy the bodies own infected cells, especially those containing viruses. They may attack cells that might form tumors. They do not eat the cell but lyse it
C). Inflammatory Response
Damage to tissue by physical injury will trigger an inflammatory response.
Small blood vessels in the area will dilate and become leakier. This causes the redness and heat of the infected area. This enhances the migration of phagocytes into the area. Neutrophils arrive first, followed by monocytes that develop into macrophages. Clotting proteins seal off the infected area.
Injured cells release HISTAMINE which induces the dilation of the capillaries.
Sometimes white blood cells release chemicals called pyrogens. They act on the bodies thermostat and raise the temperature in an effort to kill the microorganism.
Antimicrobial Proteins
Interferons: Acts in warning other cells of a viral invasion. It is produced by infected cells.
Complement: Circulate in the body in an inactive form. They are activated by chemical markers, or the onset of the immune response.
SPECIFIC DEFENSE MECHANISMS:
Immune Response = a recognition system that distinguishes "self" form "non-self".
Antigen = Foreign substance.
Antibody = specific defensive proteins which help to counter antigens is various ways.
Immunity = protection afforded to an organism by previous exposure to an antigen.
Active Immunity = Immunity conferred by an encounter with the actual virus or bacterium. The body actually produces antibodies in its own defense.
Passive Immunity = Temporary acquired antibodies passed on to the organism. No antigen is passes on.
The Immune response is governed by 2 different parts of the immune system.
Humoral Immunity: results in the production of antibodies that circulate around the body in blood and lymph (humors).Defends against: free bacteria and viruses.
Cell-mediated Immunity: defense activities are carried out by specialized cells circulating around the body. Defends against: host cells infected with bacteria and viruses, fungi and protozoans, tissue transplants, own cancer cells.
