A&P 21: The Immune System - Innate & Adaptive Body Defenses Flashcards Preview

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Flashcards in A&P 21: The Immune System - Innate & Adaptive Body Defenses Deck (129)
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1
Q

Immunity

A

resistance to disease

2
Q

Innate (nonspecific) defense system

A

system that responds within minutes to protect the body from all foreign substances

3
Q

Adaptive (specific) defense system

A

an “elite fighting force” equipped with high-tech weapons to attack particular foreign substances

4
Q

Immune system

A

functional system (rather than an organ system) including a diverse array of molecules plus trillions of immune cells (esp lymphocytes) that inhabit lymphoid tissues and circulate in body fluids

5
Q

Pathogens

A

harmful or disease-causing microorganisms

6
Q

Neutrophils

A

most abundant type of WBC; become phagocytic on encountering infectious material in the tissues

7
Q

Macrophages

A

most voracious phagocytes; “big eaters”; derive from WBC’s called monocytes

8
Q

Monocytes

A

WBC’s that become macrophages upon leaving the bloodstream & entering the tissues

9
Q

Phagosome

A

vesicle formed as a result of phagocytosis

10
Q

Phagolysosome

A

phagosome + lysosome

11
Q

Opsonins

A

complement proteins or antibodies that provide “handles” to which phagocyte receptors can bind

12
Q

Opsonization

A

process of a pathogen becoming coated with opsonins (“to make tasty”); greatly accelerates phagocytosis of a pathogen

13
Q

Respiratory burst

A

promotes killing of pathogens by liberating a deluge of highly destructive free radicals (including superoxide), producing oxidizing chemicals (H2O2 and a substance identical to household bleach), and increasing the phagolysosome’s pH and osmolarity, which activiates other protein-digesting enzymes that ingest the invader

14
Q

Natural killer (NK) cells

A

“police” the body in blood and lymph; a unique group of defensive cells that can lyse and kill cancer cells and virus-infected body cells before the adaptive immune system is activated; “pit bulls” of the defense system; part of a small group of large granular lymphocytes

15
Q

Inflammatory response

A

triggered whenever body tissues are injured by physical trauma, intense heat, irritating chemicals, or infection by viruses, fungi, or bacteria

16
Q

Mast cells

A

key component of the inflammatory response; release the potent inflammatory chemical histamine

17
Q

Histamine

A

potent inflammatory chemical released by mast cells

18
Q

Toll-like receptors (TLRs)

A

surface membrane receptors; play a central role in triggering immune responses

19
Q

Kinins, prostaglandins, and complement

A

inflammatory chemicals

20
Q

Hyperemia

A

congestion with blood

21
Q

Exudate

A

fluid containing clotting factors and antibodies

22
Q

Leukocytosis-inducing factors

A

injured cells release these chemicals

23
Q

Leukocytosis

A

increase in white blood cells, characteristic of inflammation

24
Q

Margination

A

phenomenon of phagocytes clinging to the inner walls (margins) of the capillaries and postcapillary venules

25
Q

Diapedesis

A

process of continued chemical signaling prompting the neutrophils to flatten and squeeze between the endothelial cells of the capillary walls

26
Q

Chemotactic agents

A

inflammatory chemicals act as “homing devices”

27
Q

Chemotaxis

A

neutrophils and other WBCs migrating up the gradient of chemotactic agents to the site of injury is a positive version of this

28
Q

Pus

A

creamy yellow mixture of dead or dying neutrophils, broken-down tissue cells, and living and dead pathogens; may accumulate in a wound

29
Q

Antimicrobial proteins

A

enhance our innate defenses by attacking microorganisms directly or by hindering their ability to reproduce; most important of these are interferons and complement proteins

30
Q

Interferons (IFNs)

A

some infected cells can secrete these small proteins to help protect cells that have not yet been infected

31
Q

Complement system (complement)

A

a group of at least 20 plasma proteins that normally circulate in the blood in an inactive state; include C1-C9, factors B, D, and P, and several regulatory proteins

32
Q

Classical pathway

A

1 of 3 pathways by which complement can be activated; involves antibodies (water-soluble protein molecules that the adaptive immune system produces to fight off foreign invaders)

33
Q

Lectin pathway

A

1 of 3 pathways by which complement can be activated; involves lectins (water-soluble protein molecules that the innate immune system produces to recognize foreign invaders)

34
Q

Alternative pathway

A

1 of 3 pathways by which complement can be activated; triggered when spontaneously activated C3 and other complement factors interact on the surface of microorganisms

35
Q

Membrane attack complex (MAC)

A

group of complement proteins, the insertion (into the cell membrane) of which is triggered by C3b binding to the target cell’s surface; forms and stabilizes a hole in the membrane that allows a massive influx of water, lysing the target cell

36
Q

Fever

A

abnormally high body temperature; a systemic response to invading microorganisms

37
Q

Pyrogens

A

“fire”; chemicals that act on the body’s thermostat (a cluster of neurons in the hypothalamus) - raising the body’s temperature above normal

38
Q

Adaptive immune system

A

the body’s built in specific defense system that stalks and eliminates with nearly equal precision almost any type of pathogen that intrudes into the body

39
Q

Humoral immunity

A

antibody-mediated immunity; provided by antibodies present in the body’s humors (fluids)

40
Q

Cellular immunity

A

cell-mediated immunity; when lymphocytes rather than antibodies defend the body; has cellular targets

41
Q

Antigens

A

substances that can mobilize the adaptive defenses and provoke an immune response; ultimate targets of all adaptive immune responses

42
Q

Nonself

A

intruders into the body; antigens

43
Q

Complete antigens

A

functions in immunocgenicity and reactivity

44
Q

Immunogenicity

A

ability to stimulate specific lymphocytes to proliferate

45
Q

Reactivity

A

ability to react with the activated lymphocytes and the antibodies released by immunogenic reactions

46
Q

Hapten

A

incomplete antigen; troublesome small molecule; unless attached to protein carriers, they have reactivity but not immunogenicity; certain drugs (PCN), chemicals in poison ivy, animal dander, detergents, cosmetics, and a number of common household and industrial products act as these

47
Q

Antigenic determinants

A

the parts of the antigen that are immunogenic

48
Q

Self-antigens

A

assuming your immune system has been properly “programmed,” these are not foreign or antigenic to you, but are strongly antigenic to other individuals (basis of transfusion reactions and graft rejection)

49
Q

MHC Proteins

A

group of glycoproteins among the cell surface proteins that identify a cell as self; each has a deep groove that holds a peptide (either a self-antigen or a foreign antigen)

50
Q

Major Histocompatibility Complex (MHC)

A

codes for MHC proteins

51
Q

B lymphocytes (B cells)

A

oversee humoral immunity

52
Q

T lymphocytes (T cells)

A

non-antibody-producing lymphocytes that constitute the cellular arm of adaptive immunity

53
Q

Immunocompetence

A

each lymphocyte must become able to recognized its one specific antigen by binding to it

54
Q

Self-tolerance

A

each lymphocyte must be relatively unresponsive to self-antigens so it does not attack the body’s own cells

55
Q

Primary lymphoid organs

A

the lymphoid organs where they lymphocytes become immunocompetent (thymus and bone marrow)

56
Q

Secondary lymphoid organs

A

all other lymphoid organs besides thymus and bone marrow

57
Q

Positive selection

A

1st of 2 tests a developing T lymphocyte must pass; ensures that only T cells that are able to recognize self-MHC proteins survive

58
Q

Negative selection

A

2nd test; ensures that T cells do not recognize self-antigens displayed on self-MHC

59
Q

Naive

A

immunocompetent B and T cells that have not yet been exposed to antigen; these B & T cells are exported from the primary lymphoid organs to seed/colonize the secondary lymphoid organs (lymph nodes, spleen, etc)

60
Q

Clonal selection

A

when an antigen binds to the particular lymphocyte that has a receptor for it, the antigen selects that lymphocyte for further development; if the proper signals are present, the selected lymphocyte will activate to complete its differentiation

61
Q

Clone

A

once activated, the lymphocyte rapidly proliferates to form this army of cells all exactly like itself and bearing the same antigen-specific receptors

62
Q

Effector cells

A

most members of the clone become these cells that actually do the work of fighting infection

63
Q

Memory cells

A

a few members of the clone become these cells that are able to respond quickly after any subsequent encounter with the same antigen

64
Q

Antigen-presenting cells (APCs)

A

cells that engulf antigens and then present fragments of them, like signal flags, on their own surfaces where T cells can recognize them

65
Q

Dendritic cells

A

cells found at the body’s frontiers (ex. skin) acting as mobile sentinels; very efficient antigen catchers; most effective antigen presenter known

66
Q

Plasma cells

A

antibody-secreting effector cells of the humoral response; develop the elaborate internal machinery (RER) needed to secrete antibodies at the rate of 2000 molecules per second; does this 4-5 days then dies

67
Q

Memory cells

A

clone cells that do not become plasma cells become these long-lived cells; can mount an almost immediate humoral response if they encounter the same antigen again in the future

68
Q

Primary immune response

A

cellular proliferation and differentiation; occurs on 1st exposure to a particular antigen; typically has a lag period of 3-6 days after the antigen encounter

69
Q

Secondary immune response

A

if/when someone is reexposed to the same antigen, this faster, more prolonged, more effective response occurs

70
Q

Immunological memory

A

memory cells provide this because they are sensitized and already on alert

71
Q

Active humoral immunity

A

when B cells encounter antigens and produce antibodies against them, this type of immunity is exhibited

72
Q

Vaccines

A

artificially acquired active immunity by receiving dead or attenuated pathogens

73
Q

Passive humoral immunity

A

differs from active immunity, both in the antibody source and in the degree of protection; instead of being made by your plasma cells, ready-made antibodies are introduced into your body; conferred naturally on a fetus or infant when the mother’s antibodies cross the placenta or are ingested with the mother’s milk; can be conferred artificially by administering gamma globulin, harvested from plasma

74
Q

Antibodies

A

immunoglobulins (Igs); constitute the gamma globulin part of blood proteins

75
Q

Antibody monomer

A

4 looping polypeptide chains linked by disulfide bonds combine to form this molecule, with 2 identical halves; whole molecule is T or Y-shaped

76
Q

Heavy (H) chains

A

2 of the chains of an antibody monomer are identical to each other and long; have a flexible hinge region at their approximate middles

77
Q

Light (L) chains

A

2 of the chains of an antibody monomer are identical to each other and half as long as the other type of chain

78
Q

Variable (V) region & Constant (C) region

A

each chain forming an antibody has these 2 regions, 1 on each end

79
Q

Antigen-binding site

A

in each arm of the antibody monomer, the V regions of the heavy and light chains combine to form this site shaped to fit a specific antigenic determinant; each antibody monomer has 2 of these sites

80
Q

Antigen-antibody (immune) complexes

A

common event in all antibody-antigen interactions is the formation of these complexes

81
Q

Neutralization

A

simplest defense mechanism; occurs when antibodies block specific sites on viruses or bacterial exotoxins (toxic chemicals secreted by bacteria); as a result, the virus or exotoxin can’t bind to receptors on tissue cells

82
Q

Agglutination

A

clumping caused by cell-bound antigens being cross-linked

83
Q

Precipitation

A

soluble molecules (not cells) are cross-linked into large complexes that settle out of solution; much easier for phagoctyes to capture and engulf than are freely moving antigens

84
Q

IgM

A

1st immunoglobulin class secreted by plasma cells during the primary response; readily fixes and activates complement; monomer and pentamer forms

85
Q

IgA

A

dimer referred to as secretory ___; found in body secretions such as saliva, sweat, intestinal juice, and milk; helps stop pathogens from attaching to epithelial cell surfaces (including mucous membranes and the epidermis)

86
Q

IgD

A

monomer found on the B cell surface; functions as a B cell antigen receptor (as does IgM)

87
Q

IgG

A

most abundant antibody in plasma (75-85%) of circulating antibodies; main antibody of both secondary and late primary responses; readily fixes and activates complement

88
Q

IgE

A

monomer; stem end binds to mast cells or basophils; antigen binding to its receptor end triggers these cells to release histamine and other chemicals that mediate inflammation and an allergic reaction

89
Q

Monoclonal antibodies

A

produced by descendants of a single cell; pure antibody preparations specific for a single antigenic determinant

90
Q

Hybridomas

A

monoclonal antibodies are made by fusing tumor cells and B lymphocytes; the resulting cell hybrids are called this; like tumor cells, they proliferate indefinitely in culture; like B cells, they produce a single type of antibody

91
Q

CD4 Cells

A

type of effector cell that usually becomes helper T cells (TH) that help activate B cells, other T cells, and macrophages, and direct the adaptive immune response

92
Q

CD8 cells

A

type of effector cell that usually becomes cytotoxic T cells (TC) that destroy any cells in the body that harbor anything foreign

93
Q

Class I MHC Proteins

A

proteins found on the surface of virtually all body cells except red blood cells; each has a groove that holds an antigen - a protein fragment 8 or 9 amino acids long

94
Q

Endogenous antigens

A

all antigens displayed on class I MHC proteins are these fragments of proteins synthesized inside the cell

95
Q

Class II MHC Proteins

A

second, less widespread type of protein typically found only on the surfaces of cells that present antigens to CD4 cells: dendritic cells, macrophages, and B cells

96
Q

Exogenous antigens

A

antigens from outside the cell that have been engulfed by the cell that displays them

97
Q

T Cell Antigen Receptors (TCRs)

A

receptors that bind to an antigen-MHC complex on the surface of an APC; has variable and constant regions but consists of 2 rather than 4 polypeptide chains

98
Q

Co-stimulatory signals

A

other molecules that appear on the surfaces of APCs in tissues that are damaged or invaded by pathogens

99
Q

Anergy

A

state of unresponsiveness to an antigen

100
Q

Cytokines

A

the chemical messengers involved in cellular immunity belong to a group of molecules called this; a general term for mediators that influence cell development, differentiation, and responses in the immune system; include interferons and interleukins; include hormone-like or paracrine-like glycoproteins released by a variety of cells

101
Q

Interleukin-I (IL-1)

A

released by macrophages; stimulates T cells to liberate interleukin 2 (IL-2) and to synthesize more IL-2 receptors

102
Q

Interleukin-II (IL-2)

A

key growth factor; sets up a positive feedback cycle that encourages activated T cells to divide even more rapidly

103
Q

Helper T (TH) cells

A

play a central role in adaptive immunity, mobilizing both its humoral and cellular arms

104
Q

T cell-independent antigens

A

antigens that activate B cells solely by binding to them; tend to be weak and short-lived

105
Q

T cell-dependent antigens

A

most antigens; require T cell help to activate the B cells to which they bind

106
Q

Cytotoxic T (TC) cells

A

activated CD8 cells; only T cells that can directly attack and kill other cells

107
Q

Lethal hit

A

once cytotoxic T cells recognize their targets, there are 2 major mechanisms - 1 involves perforins and granzymes; the other involves binding to a specific membrane receptor on the target cell that stimulates the target cell to undergo apoptosis

108
Q

Immune surveillance

A

NK cells and TC lymphocytes roam the body, adhering to and crawling over the surfaces of other cells, examining them for markers they might recognized, a process called this

109
Q

Regulatory T (Treg) cells

A

dampen the immune response; act either by direct contact or by releasing inhibitory cytokines such as IL-10 and TGF-Beta

110
Q

Autografts

A

tissue grafts transplanted from one body site to another in the same person

111
Q

Isografts

A

grafts donated to a patient by a genetically identical individual (only example = identical twins)

112
Q

Allografts

A

grafts transplanted from individuals who are not genetically identical but belong to the same species

113
Q

Xenografts

A

grafts taken from another animal species, such as transplanting a baboon heart into a human

114
Q

Chimeric immune system

A

way to induce tolerance by temporarily suppressing the recipient’s bone marrow then dousing it with bone marrow from the same donor as the new organ in the hope that this combined immune system will treat the transplanted organ as self

115
Q

Immunodeficiency

A

congenital or acquired condition that impairs the production or function of immune cells or certain molecules, such as complement or antibodies

116
Q

Severe combined immunodeficiency syndromes (SCID)

A

the most devastating congenital immunodeficiencies are a group of related disorders called this; result from various genetic defects that produce a marked deficit of B and T cells

117
Q

Acquired immune deficiency syndrome (AIDS)

A

most devastating of the acquired immunodeficiencies; cripples the immune system by interfering with the activity of helper T cells

118
Q

Human immunodeficiency virus (HIV)

A

AIDS is caused by this virus transmitted in body secretions, especially blood, semen, and vaginal secretions; also present in saliva and tears; destroys TH cells, depressing cellular immunity

119
Q

Autoimmunity

A

when the body produces antibodies (autoantibodies) and cytotoxic T cells that destroy its own tissues

120
Q

Autoimmune disease

A

if a disease state results from autoimmunity, it is called this

121
Q

Hypersensitivities

A

result when the immune system damages tissue as it fights off a perceived threat (such as pollen or animal dander) that would otherwise be harmless to the body

122
Q

Immediate hypersensititivies

A

acute (type I) hypersensitivities; = allergies

123
Q

Allergen

A

antigen that causes an allergic reaction

124
Q

Anaphylactic shock

A

systemic response, fairly rare; occurs when the allergen directly enters the blood and circulates rapidly through the body (ex. bee sting, spider bite, injection of a foreign substance such as PCN or other drugs that act as haptens)

125
Q

Subacute hypersensitivities

A

caused by antibodies (IgG and IgM); slower onset (1-3 hours after antigen exposure) and the reaction lasts longer (10-15 hours)

126
Q

Cytotoxic (type II) reactions

A

reactions that occur when antibodies bind to antigens on specific body cells and stimulate phagocytosis and complement-mediated lysis of the cellular antigens; may occur after a patient has received a transfusion of mismatched blood and complement lyses the foreign RBCs

127
Q

Immune-complex (type III) hypersensitivities

A

result when antigens are widely distributed through the body or blood and the huge number of insoluble antigen-antibody complexes formed can’t be cleared from a particular area (may reflect a persistent infection or an autoimmune disease); ex. = Farmer’s lung (induced by inhaling moldy hay) and glomerulonephritis of systemic lupus erythematosus

128
Q

Delayed (type IV) hypersensitivity reactions

A

caused by T cells; take longer to appear (1-3 days) than antibody-mediated hypersensitivity reactions; inflammation and tissue damage result from the action of cytokine-activated macrophages and sometimes cytotoxic T cells

129
Q

Allergic contact dermatitis

A

most familiar example of delayed hypersensitivity reactions which follow skin contact with poison ivy, some metals, certain cosmetics and deodorant chemicals; these agents act as haptens, and after they diffuse through the skin and attach to self-proteins, the immune system perceives them as foreign

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