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Chapter 21

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