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Flashcards in Final Deck (99):
1

two different types of immune system

innate (nonspecific defenses) and acquired

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first line of defense (definition)

surface protection composed of anatomical and and physiological barriers that keep microbes from penetrating sterile body compartments

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second line of defense (definition)

cellular and chemical system that comes immediately into play oif infectious agents make it past the surface defenses. EX- phagocytes that engulf foreign matter and destroy it, and inflammation that holds infections in check

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first line of defense (examples)

physical barriers, chemical barriers, genetic components

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second line of defense (examples)

inflammatory response (includes fever), interferons, phagocytosis, complement

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third line of defense (definition)

specific host defenses that must be developed uniquely for each microbe through the action of specialized white blood cells. this form of immunity is usually long term and has memory.

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third line of defense (examples)

antibodies, B cells, T cells, accessory cells, cytokines

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innate, nonspecific immunity

first and second lines of defense, defenses you are born with, always on guard, do not improve with repeated exposure, involve barriers, inflammatory, and phagocytic defenses

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physical barriers exapmles

first line of defense, thick skin, cilia, mucus, secretions

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chemical barriers examples

sebaceous secretions, lysozyme in tears, lactic acid and electrolyte concentrations of sweat, skin's acidic pH and fatty acid content, HCL in the stomach, digestive juices and bile in the intestine, semen (antimicrobial chemical, acidic pH in the vagina

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genetic barrier example

differences in susceptibility, genetically immune to the diseases of other hosts, specificity of viruses (viruses can only invade certain types of hosts)

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immunology

study of all features of the body's second and third lines of defense

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healthy functioning immune system is responsible for

1. surveillance of the body
2. recognition of foreign materials
3. destruction of entities deemed to be foreign

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self and non-self cells

white blood cells must distinguish self from non-self cells, evaluates cells by examining markers on their surfaces

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parts of the body involved in immune defenses

1. Reticuloendothelial system (RES)
2. Extracellular fluid (ECF)
3. Blood stream
4. lymphatic system (communication between compartments is essential)

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Reticuloendothelial system

network of connective tissue fibers, provides a passageway within and between tissues and organs (thymus, lymph nodes, spleen)

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lymphatic system

compartmentalized network of vessels, cells, and specialized accessory organs, transports lymph through a system of vessels and lymph nodes

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major functions of the lymphatic system

1. provides return of extracellular fluid to the circulatory system
2. acts as a drain-off system for the inflammatory response
3. renders surveillance, recognition, and protection against foreign materials. houses the lymphocytes

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lymph

plasma-like fluid formed when blood compartments move out of blood vessels into the extracellular spaces and diffuse or migrate into the lymphatic capillaries,

composition parallels that of plasma, but without red blood cells

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lymphatic vessels

located along the lines of blood vessels, similar to thin-walled veins, high numbers in hands and feet and around the breast, flow of lymph is in one direction only- from extremities toward the heart, lymph moves by contraction of skeletal muscles through which the lymphatic ducts went their way

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lymph nodes

small, encapsulated, bean-shaped organs, usually in clusters along lymphatic channels and large blood vessels of the thoracic and abdominal cavities
major aggregations: axillary nodes, inguinal nodes, cervical nodes

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spleen

similar to lymph nodes but it filters blood instead of lymph, filters pathogens and debris from the blood

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thymus

site of T-cells maturation, high rates of activity and growth until puberty, shrinks gradually after adulthood

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leukocytes

white blood cells, granulogcytes and agranulocytes

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granulocytes

large cytoplasmic granules, lobed nucleus
1. neutrophils
2. basophils
3. eosinphils

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agranulocytes

very small granules, rounded nucleus
1. T cells
2. B cells
3. monocytes

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neutrophil

most common leukocyte
high numbers in blood and tissue
phagocytizes bacteria- granules are digestive enzymes
acts like a greneade- kills everything including itself
first to arrive during an immune response (inflammation)

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Eosinophil

present in bone marrow and spleen
attach and destroy eukaryotic pathogens (multicellular parasites)
associated with inflammation and allergies
granules contain histamine

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basophil

low in numbers in the body- less than 0.5%
function similar to eosinoophils (contains histamine)
localized basophils are called mast cells
important in allergic responses

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agranulocytes

lymphocytes: T and B cells
2nd most common leukocyte
T cells-
B cells-

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T cells

cell-mediated immunity
directly kill cells
ex. killer t cells

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B cells

antibody (humoral)- mediated immunity
produce antibodies and memory cells

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monocytes

precursor cells that become macrophages "big eater" circulate as monocytes in the blood, lymph, and interstitial fluid, discharged by bone marrow into bloodstream, live as phagocytes for a few days, then differentiate into macrophages, long-lived and actively moble

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monocytes responsible for

many specific and nonspecific phagocytic and killing functions
kill 1 invader at a time. not destroyed in the process
processing foreign molecules and presenting them to lyphocytes (T and B cells)
secreting biologically active compounds that assist mediate, attract, and inhibit immune cells and reactions

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inflammatory response

reaction to any traumatic event in the tissue

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classic signs and symptoms to inflammatory response (5)

rubor (redness)
calor (warmth)
tumor (swelling)
dolor (pain)

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functions of inflammation

1. mobilize and attract immune components to the site of injury
2. set in motion mechanisms to repair tissue damage and localize and clear away harmful substances
3. destroy microbes and block their further invasion

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vascular reactions

cytokines released by blood cells, tissue cells, and platelets in the injured area
vasoactive mediators affect the endothelial cells and smooth muscle cells of blood vessels
arterioles constricted at first but quickly vasodialation takes place to bring WBC's to the area
chemokines attract white blood cells

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exudates

fluid that escapes through gaps in walls of vessels

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edema

accumulation of exudates

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diapedesis

how WBC leave the blood vessels and into tissue spaces

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chemotaxis

tendency of WBC to migrate in response to a specific chemical stimulus

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benefits of edema and chemotaxis

dilutes toxic substances
traps microbes and prevents further spreading
phagocytosis occurs immediately
certain bacteria are pyogeneic (pus-forming) and attract neutrophils

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resolution of inflammation

attracts a collection of monocytes, lymphocytes, and macrophages to the reaction site

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macroophages

result of inflammation: clear pus, cellular debris, dead neutrophils, and damaged tissue from the area

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B lymphocytes

produce antibodies

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T lymphocytes

kill intruders directly

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scar tissue

late in the process the tissue is repaired or replaced by connective tissue

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fever - definition

adjunct to inflammation, human bacteria do not grow well at high temps, optimum temp is 37C

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initiation of fever

macropohages send a signal called pyrogen to the brain

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pyrogen

sets the hypothalamic theromstat to a higher setting, triggers muscles to increase heat production, triggers peripheral arterioles decrease heat loss through vasoconstriction, these changes cause fever, keeps the heat in

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benefits of fever

inhibits multiplication of temperature sensitive microorganisms, impedes the nutrition of bacteria by reducing the availability of iron, increases metabolism and stimulates immune reactions

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bad effects of fever

feber curbs microbial growth but it can be dangerous because it might inactivate critical cellular enzymes

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phagocytosis

discovers microbes, partiulate matter, and injured or dead cells, ingests and eliminates these materials
extracts immunogenic information (antigens) from foreign matter for presentation

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phagocytosis stages

1. chemo taxis
2. binding to recognition receptors Engulfment
3. phagosome formation (contains the pathogen in side of the phagocyte)
4. lysosomal fusion- phagolysosome (destroys the pathogen in protected vesicle inside the phagocyte)
5. destruction
6. waste elimination

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interferon

proteins that kill invading microbes
act as messengers to other cells int he vicinity of an infection to prevent a virus from spreading to new cells
bind to cell infected host cell surfaces and induce changes in genetic expression
they are unable to make new viruses in the cells that received the interferon message

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complement system

proteins that kill invading microbes, 26 different proteins that circulate freely in the plasma in an inactive state until they encounter fungal or bacteria cell wall

aggregate to form a membrane attack complex that forms a protein the foreign cell's membrane, causing water to rush in and lyse the cell

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steps of protein attack on invaders- complement

1. initiation
2. amplification
3. cascade
4. polymerization
5. membrane attack

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adaptive/specific immunity

acquired only after an immunizing event such as an infection or vaccination

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immunocompetence

ability of the body to react to foreign non-self substances, development of B and T lymphocytes, lymphocytes become specialized for reacting only to one specific antigen

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features of the third line of defense

1. specificity
2. memory

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five main stages of development

1. lymphocyte development and differentiation
2. presentation of antigens (by macrophages)
3. challenge of B and T lymphocytes by antigens
4. B lymphocytes and the production/activities of antibodies
5. T lymphocyte responses- usually end in direct killing

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steps acquired in immunity

1. lymphocyte development
2. presentation of antigens
3. challenge of B cells and T cells
4. antibodies and cell-mediated immunity

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macrophages

initiate the immune response, inspect the surfaces of all cells they encounter, act as antigen presenting cell

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major histocompatibility protins

special marker proteins on the surface of the cell body, same on all cells in that body, "self" markers enable the individual's immune system to distinguish its cells from foreign cells

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MHC- Self- Markers

MHC proteins are found on host cells, unique "self" antigens, if absent, the cells will be destroyed by the immune system

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stimulants of cell division

exposure of non-self antigen to the T and B lymphocytes

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clonal selection

T and B cells produced that are specific to the antigen

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primary immune response

slow to develop and produce a t-cell response and b-cell respnse (antibodies and memory cells)

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secondary immune response

more effective when the pathogen is encountered again. large clone of lymphocytes that can recognize a pathogen remains

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t cell lymphocytes

(cell-mediated response) originate in the bone marrow but migrate to the thymus after maturation, recognize microorganisms by markers (antigens) on their surface, some will be helper t and killer t

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B cell lymphocytes

(humoral response) complete their maturation in the bone marrow and then an antigen is encountered they produce antibodies (protiens, not whole cells, y shaped protiens, have antigen binding sites on the y, lock and key fit only to that pathogen) and memory cells, these antibodies coat the antigen and mark the cell for destruction, memory cells serve as immune memory in case of second exposure, make plasma clones (produce antibodies against pathogen) and memory cell clones (create lasting memory)

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antibody function

bacterial cell, opsonization, neutralization, agglutination (blood clots, whole cells clump), complement fixation (lyse), precipitation (aggregates, not whole cell clumps)

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immunoglobulin G

main antibody in blood plasma, activates complement, rapidly responds to second exposure of an antigen, cross placenta, found in serum, 80%

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immunoglobulin A

13%, no fixing (activation) of complement, antibody found in external secretions, important in mucosal defenses

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immunoglobulin M

found in serum, 6%, fixes complement, promotes aggluination (clumping) reactions, fist one made during an infection

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immunoglobulin D

not found in serum, 1%, located on surface of B cells, acts as a receptor: serves as antigen receptors on the B cells

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Immunoglobulin E

sticks to mast cells, produced in response to allergens and parasitic worm defenses, promotes the release of histamine

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first exposure

latent period, lack of antibodies synthesis, IgM first followed by IgG

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second exposure to the same antigen

antibody synthesis, titer, and length of antibody persistence is rapid and amplified

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active immunity

antigen activates B and T cells, memory cells produced, long-term protection

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passive

natural or artificial, receive antibodies from another individual or animal, no memory cells, no antibody production, short-term protection

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natural immunity- active

direct exposure due to infection, develop a specific immune response, may suffer undesired consequences

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natural immunity- passive

protection from mom, mother's IgG crosses the placenta in utero, IgA present in the colostrum (first breast milk)

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artificial immunity- active

vaccinations, stimulates immune response with memory

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artificial immunity- passive

injecting immune serum from one patient in to another patient, attempt to neutralize the threat, immunotherapy, no memory

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vaccination

introduction of a dead or disabled pathogen or a subunit of a pathogen, vaccination triggers an immune response against the pathogen without an infection occuring

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subunit vaccine

genetic engineeered, "piggyback" or "trojan horse"

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recombinant DNA techniques in vaccines

made of a harmless virus that has pathogen gene inserted so that the virus displays the pathogen protein on its surface. the body responds by making an antibody against that antigen, as well as memory cells to recall that antigen

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flu viral genes

some viruses change their antigen makeup and prevent detection even after a vaccination, code for surface proteins mutate quickly

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influenza- hemagglutinin

has agglutinating action on red blood cells
binds to a host cell receptors of respiratory mucosa, spike occurs in envelope

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influenza- neuraminidase

breaks down mucus on respiratory tract,
assists in virus budding and release, keeps viruses from sticking together, participate in host cell fusion, spike occurs in envleope

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influenza- antigenic drift

gradual changing of amino acid composition of influenza antigens, results in decreased ability of host memory cells to recognize them

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influenza- antigenic shift

swapping out of one of the strands of viral RNA with a gene or strand from another virus, no recognition by host memory cells, influenza pandemic

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whole cell or virus

live attenuated cells or viruses, altered so it is less virulent or harmless, killed cells or inactivated viruses

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antigenic molecules (subunits

subunits cultured from cells or viruses, lab synthesized subunits

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herd immunity

collective immunity through mass immunization- confers indirect protection on the nonimmune members, prevents epidemics

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requirements of a vaccine

low level of side effects, protect agains natural exposure, stimulate B cell and T cell, lon germ effects, does not require numerous doses or boosters, inexpensive, long shelf life, easy to administer

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inactivated vs attenuated

dead organisms are safest, less effective immunogens, live organisms have a better immune response, danger that they may mutate back to virulent form