The Immune System Flashcards

1
Q

What is immunity?

A

The body’s ability to resist or eliminate potentially pathogenic agents or abnormal cells

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2
Q

3 functions of the immune system

A

Defense, eliminate, surveillance

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3
Q

What are the 2 types of immune responses

A

Innate and adaptive (nonspecific and specific)

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4
Q

Barriers of the innate immune response

A

Physiological and anatomic (phagocytic, inflammatory, and intact epithelium)

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5
Q

Innate vs acquired: receptors

A

Not rearranged, rearranged

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6
Q

Innate vs acquired: cells

A

Macrophages, neutrophils and NK cells; CD4 cells, CD8 cells, B cells

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7
Q

Innate vs acquired: effector mechanisms

A

Innate: Phagocytosis, cell recruitment, macrophage activation, pathogen destruction
Adaptive; complement activation, cytotoxicity, pathogen destruction

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8
Q

Physical barriers of the innate response

A

Skin, mucous membranes, temperature

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9
Q

Chemical barriers of the innate response (5)

A

Lysozyme, lactoferrin, interferon, plasma proteins (complement), defensins

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10
Q

Leukocyte barriers of the innate response (5)

A

Neutrophils, macrophages, eosinophils, mast cells, NK cells

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11
Q

8 nonimmunologic host defenses

A

Tears, mucus, defensins, intestinal peristalsis, ciliated epithelium, gastric acid, microbial flora, intact skin

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12
Q

What are defensins

A

Antibacterial peptides produced by certain epithelial cells

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13
Q

What is the role of lactoferrin

A

Reduce proliferation

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14
Q

What is the role of interferon

A

Cytokines (proteins) released by cells in response to pathogens or tumor cells, they affect virus replication

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15
Q

What is the role of NK cells

A

Destroy virus infected and cancer cells, nonphagocytic

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16
Q

What chemicals do NK cells form their cytoplasmic granulea

A

Perforins and granzymes

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17
Q

How do NK cells enhance the inflammatory response

A

They secrete cytokines, IFN-gamma, TNF, GM-CSF

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18
Q

How are normal cells not killed by NK cells

A

Inhibitory signals from normal MHC class 1 molecules override activating signals

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19
Q

What do NK cells bind to

A

MHC class I receptors

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20
Q

What participates in the activation of NK cells

A

IFN alpha and beta (from virus infected cells) and IL12 (from macrophages)

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21
Q

2 divisions of adaptive response

A

Humoral (anti-body mediated, B cells) and cellular (cell-mediated, T cells)

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22
Q

2 types of immunity

A

Passive (colostrum and serum) and active (vaccines)

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23
Q

Central lymphoid tissue organs function and examples

A

Where lymphocytes mature and become competent, bone marrow and thymus

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24
Q

Peripheral lymphoid organ function and examples

A

Where adaptive immune responses to microbes are located, lymph nodes, spleen, tonsils

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25
Q

What comes from the bone marrow

A

Lymphoid stem cells (B, T and NK cells) and myeloid stem cells (monocytes, dendritic cells, granulocytes)

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26
Q

Function of B lymphocytes

A

Neutralization of microbes, phagocytosis, complement activation

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27
Q

Function of helper T lymphocytes

A

Activation of macrophages, inflammation, activation of T and B lymphocytes

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28
Q

Function of cytotoxic T lymphocytes

A

Killing of infected cells

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29
Q

Function of regulatory T lymphocytes

A

Suppression of immune response

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30
Q

What are lymphocytes in the thymus called

A

Thymocytes

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31
Q

What is the thymus responsible for

A

Developing immature T cells into immunocompetent T cells

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32
Q

What do lymphoid stem cells lack when they enter the thymus

A

Surface antigens, including T cell antigen receptor complex and mature T cell markers (CD4 and CD8)

33
Q

What results in immature T cells

A

Progenitor cells undergoing development into descendant cells with rearranged alpha and beta genes of the TCR

34
Q

What forms the TCR complex

A

TCR and CD3 molecules

35
Q

2 major functions of the spleen

A

Destruction of old RBC and it is a major site for mounting immune responses

36
Q

What brings antigens to the spleen

A

Migratory macrophages and dendritic cells (present them to T and B cells)

37
Q

Red pulp

A

Blood vessels arranged to facilitate removal of old and damaged RBCs

38
Q

White pulp

A

Lymphocytes and accessory cells

39
Q

Lymph nodes are composed mostly of…

A

T cells, B cells, dendritic cells and macrophages

40
Q

What is an antigen

A

A substance that induces a specific immune response and reacts with the products of the response

41
Q

What is an antigenic determinant

A

A specific sit of an antigen that binds to an antibody

42
Q

A single immune response to an antigen is termed…

A

Monoclonal

43
Q

What are 4 steps in the humoral response

A
  1. APCs (macrophages) present
  2. Activation of lymphocytes
  3. Proliferation
  4. Differentiation
44
Q

MHC II are recognized by…

A

CD4+ T cells (helper cells)

45
Q

In contrast to class I, MHC II molecules are mainly expressed on cells that present…

A

Ingested antigens and respond to T-cell help

46
Q

MHC I are recognized by…

A

CD8+ T cells (cytotoxic T cells)

47
Q

What is a key difference between where MHC I and II are expressed

A

MCH I are expressed on all cells, but MHC II are only presented on APCs

48
Q

The B cell receptor complex is composed of…

A

Membrane IgM (or IgD) and the signaling proteins Ig(alpha) and Ig(beta)

49
Q

Dendritic cells

A

Originate in bone marrow, capture antigens in peripheral sites, present antigens to CD4+ cells

50
Q

Follicular denritic cells

A

Receptor for IgG and C3b, present antigens to B cells

51
Q

What is the main function of helper T cells (CD4)

A

Potentiate the immune responses by the secretion of cytokines which activate other cells

52
Q

Th1

A

Cell mediated immunity - activation of macrophages

53
Q

Th2

A

Antibody production - activation of B lymphocytes

54
Q

Th17

A

Inflammation - recruitment of neutrophils and monocytes

55
Q

Th1 lymphocytes promote…

A

Cell mediated immunity

56
Q

Th2 lymphocytes promote…

A

Humoral immunity

57
Q

How is the concentration of antibody molecules in serum estimated?

A

By serial dilutions, how many dilutions can be made before antigen-antibody binding can no longer be detected

58
Q

What is the structure of an antigen binding domain (of an antibody)

A

Symmetric core structure, composed of 2 identical light chains and 2 identical heavy chains held together by disulfide bonds

59
Q

The Fc fragment of an immunoglobin varies between ___ but not ___

A

Antibody classes; within the same class

60
Q

What are the five classes of antibodies

A

IgA, IgD, IgE, IgG and IgM

61
Q

How can you distinguish between antibodies

A

By their heavy chain

62
Q

How many isotypes of IgG are there

A

4

63
Q

What is the only antibody to pass from the mother to the fetus via the placenta

A

IgG

64
Q

IgG is mainly produced during the…

A

Secondary immune response

65
Q

What is the first antibody produced by B cells?

A

IgM

66
Q

Where is IgG secreted?

A

In the blood

67
Q

Where is IgA found?

A

In the secretion of digestive, respiratory and genitourinary system, milk and tears

68
Q

IgD is produced by…

A

Activation of resting B cells

69
Q

Functions of IgG

A

Neutralization, precipitation, opsonization, complement activation, antibody-dependent/mediated cellular cytotoxicity

70
Q

Functions of IgM

A

Agglutination, complement activation

71
Q

Function of IgA

A

Mucosal protection

72
Q

What do follicular B cells do?

A

Make antibody responses to protein antigens that require collaboration with helper T cells

73
Q

What do marginal zone B cells do?

A

Recognize multivalent antigens, like polysaccharides, and mount primarily T-independent antibody responses

74
Q

Isotype switching requires…

A

The induction of activation-induced cytidine deaminase (AID)

75
Q

What is the function of AID (in isotype switching)

A

Converts cytosine to uracil in SSDNA

76
Q

Antibody affinity refers to…

A

The strength of any given bond between an antibody and its antigen

77
Q

Antibody avidity refers to…

A

The strength of the overall connection an antibody binds to its antigen

78
Q

Where/when do antibodies mature to high affinity?

A

During the germinal center reaction, occurs during the course of a T helper cell dependent humoral response