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body's ability to defend itself agains infections agents, foreign cells; creates a better chance to maintain homeostasis


disease causing agents that can potentially produce infection

1st line of defense

prevents entry of microorganisms using the skin, mucous membranes, keratin (resistant to acids bases and bacterial enzymes and toxins) and cilia


confront microorganisms that breach the external barriers


"crawling" with pseudopods


main phagocyte; form from monocytes; free macrophages wander throughout a region in search of cellular debris


first responders; become phagocytic when they encounter infectious matrerial like bacteria or fungi


weakly phagocytic; important in defending against parasitic worms

mast cells

bind, ingest and kill a wide range of bacteria; produce histamine

natural killer cells

large granular lymphocytes; attack cancer cells and virally infected cells by penetrateing plasma membrane with the release of perforins and other cytolytic chemicals; not phagocytic


tissue response to injury; occurs when the tissues are injured by physical trauma, intense heat, irritating chemicals or infection

acute inflammation

cardinal signs are redness, heat, swelling, pain and immobilization


inflammatory chemical; causes inflammation, vasodilation, increase speed of repair; brings helpful substances to the area


released by damaged cells; hormone like substance that participates in a wide range of body functions such as the contraction and relaxation of smooth muscle, the dilation and constriction of blood vessels, control of blood pressure, sensitize spinal neurons to pain and modulation of inflammation


fluid containing proteins, clotting factors and antibodies


neutrophils are released from bone marrow in response to leukocytosis-inducing factors released by injured cells


neutrophils cling to the walls of capillaries in the injured area


inflammatory chemicals attract neutrophils to the injury site


mixture of dead or dying neutrophils, broken-down tissue cells, and living and dead pathogens


sac of pus that is walled off by collagen fibers


protein that interferes with virus reproductive process

complement proteins

proteins that circulate in the blood in an inactive form; provides a major mechanism for destroying foreign substances in the body


abnormally high body temperature in response to invading microorganisms


chemicals released in the presence of bacteria and other substances; secreted by leukocytes and macrophages

immune response

systemic response; not limited to initial infection site; able to recognize the same antigen and mount faster stronger defensive attack

humoral immunity

provided by antibodies produced by B lymphocytes present in the body's fluids

cellular immunity

immunity associated with T lymphocytes and has living cells as its protective factor


substances that can mobilize the immune system and provoke an immune response

complete antigens

antigens that are able to stimulate the proliferation of specific lymphocytes and antibodies and to react with the activated lymphochytes and produced antibodies; can develop antibodies


incomplete antigens that are not capable of stimulating the immune response, but if they interact with proteins of the body, they may be recognized as potentially harmful; allergies

clonal selection

process of the B cell growing and multiplying to form an army of cells that are capable of recognizing the same antigen

plasma cells

antibody-secreting cells of the humoral response; most clone cells develop into them

memory cells

the clones that do not become plasma cells

primary immune response

occurs on first exposure to a particular antigen with a lag time of about 3-6 days

secondary immune response

occurs when someone is re-exposed to the same antigen; a faster, more prolonged, and more effective response

naturally acquired active immunity

occures when a person suffers through the symptoms of an infection

artificially acquired active immunity

occurs when a person is given a vaccine

naturally acquired passive immunity

occures when a mother's antibodies enter fetal circulation

artificially acquired passive immunity

occurs when a person is given preformed antibodies that have been harvested from another person


antibodies; proteins secreted by plasma cells in response to an antigen that are capable of binding to that antigen


first immunoglobulin secreted during the primary response


major immunoglobulin secreted during the secondary response; most abundant and diverse antibody; protects against bacteria, viruses, and toxins in the blood and lymph; cross the placenta and gives passive immunity to a fetus


immunoglobulin receptor for antigen on surface of B cells


immunoglobulin found in external secretions (saliva, sweat, intestinal juice and milk)


immunoglobulin that promotes release of histamine to mediate inflammation and allergic reaction

complement fixation

complement binds to antibodies attached to antigens and then leads to lysis of the cell


occurs when antibodies block specific sites on viruses or bacterial exotoxins, causing them to lose their toxic effects


occurs when antibodies cross-link to antigens on cells causing clumping


occurs when soluble molecules are cross-linked into large complexes that settle out of solution

Helper T Cells

react with macrophages and antigens directly; activate other B and T cells


include horomone-like glycoproteins released by activated T cells and macrophages; attract leukocytes to particular locations

Killer T cells

act against viral invaded cells and cancer cells; involved with foreign tissue graphs

suppressor t cells

stops or slows activity of immune system; thought to help in controlling autoimmune disease


graft from the same person


graft from a genetically identical individual (twin)


graft from a not genetically identical but same species (human)


grafts from another animal species


any congenital or acquired condition that causes immune cells, phagocytes or compliment, to behave abnormally

severe combined immunodeficiency (SCID)

marked deficiency of B and T cells

acquired immune deficiency syndrome (AIDS)

Cripples the immune system by interfering with the activity of helper Tcells.


virus that flourishes in the body and destroys the helper T cells

Autoimmune disease

The immune system loses the ability to distinguish from self and foe; includes multiple sclerosis, graves disease, Type I diabetes mellitus and rheumatoid arthritis

immediate hypersensitivies

begin within seconds after contact and last about half an hour

anaphylactic shock

body-wide or system response; bee sting, spider bite; sever systemic allergic reaction

subacute hypersensitivities

take 1-3 hours to occure and last 10-15 hours; may be caused by hair dyes; caused by antibodies

delayed hypersensitivity

reaction takes about 1-3 days to occur and may take weeks to go away; examples include deoderants, cosemetics and metals


A type of immediate hypersensitivity response that results in "weeping" skin lesions and intense itching. Onset is the first five years of life in 90% of cases. The allergen is uncertain, but familial predisposition is strong.


The process of rendering a subject immune by vaccination or injection of antiserum.


The study of immunity


the study of diseases of the immune system

septic shock

inflammatory response that is out of control; kills 175,000 people every year in the US; results from especially severe bacterial infections or more ordinary infections

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