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MCAT > Biology Ch 8. The Immune System > Flashcards

Biology Ch 8. The Immune System Flashcards

1
Q

Innate immunity

A

Composed of defenses that are always active, but they cannot target a specific invader and cannot maintain immunological memory, also called non-specific immunity, typically acts near entry points of the body

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2
Q

Immune system divisions

A

Innate and adaptive immunity

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3
Q

Nonspecific immunity

A

Composed of defenses that are always active, but they cannot target a specific invader and cannot maintain immunological memory (makes response faster next time), also called innate immunity, typically acts near entry points of the body

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4
Q

Adaptive immunity

A

Composed of defenses that take time to activate, but that can target a specific invader and can maintain immunological memory (makes response faster next time), also called specific immunity

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5
Q

Specific immunity

A

Composed of defenses that take time to activate, but that can target a specific invader and can maintain immunological memory, also called adaptive immunity

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6
Q

Skin innate immune system

A

Access a physical barrier and secretes antimicrobial compounds, like defensins, secretes sweat which has antimicrobial properties, first line of defense

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7
Q

Defensins

A

Antimicrobial compounds/antibacterial enzymes that can be found secreted from the skin

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8
Q

Bone marrow

A

Where immune cells come from –> where hematopoiesis takes place

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9
Q

Spleen

A

Location of blood storage, one site where immune responses can be mounted, where B-cells are activated

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10
Q

Lymph nodes

A

Major components of lymphatic system, one site where immune responses can be mounted, where B-cells are activated

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11
Q

Thymus

A

Site of T-cell maturation, small gland just in front of the pericardium

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12
Q

Gut-associated lymphoid tissue

A

GALT - Includes the tonsils, adenoids, Peyer’s patches in the small intestine, and lymphoid aggregates in the appendix, in close proximity to digestive system which is a site of potential pathogen invasion

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13
Q

Leukocytes

A

White blood cells involved in immune defense, divided into granulocytes and agranulocytes

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14
Q

Mucus innate immune system

A

Present on mucous membranes to trap pathogens, in the respiratory system the mucus is propelled upward by cilia and can be swallowed or expelled

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15
Q

Lysozyme

A

An antibacterial compound found in saliva and tears, a nonspecific bacterial enzyme

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16
Q

Stomach innate immune system

A

Produces acid killing most pathogens, colonization of the gut helps prevent overgrowth of pathogenic bacteria through competition

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17
Q

Complement system

A

Consists of a number of proteins in the blood that act as a nonspecific defense against bacteria, can punch holes in the cell walls of bacteria, making them osmotically unstable, can be activated through classical or alternative pathway, cannot be modified to target specific organism so still considered nonspecific defense

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18
Q

Interferons

A

Proteins given off by virally infected cells and help prevent viral replication and dispersion to nearby cells, causes nearby cells to decrease production of viral and cellular proteins, decrease permeability of cells making it harder for a virus to infect them, up regulate MHC molecules which increases antigen presentation and better detection of infected cells, responsible for many “flu like” symptoms

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19
Q

Noncellular innate immune system components

A

skin & defensins, mucus, lysozyme, GALT, complement system, interferons

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20
Q

Cellular innate immune system components

A

Macrophages, dendritic cells, natural killer cells, granulocytes including neutrophils, eosinophils, basophils

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21
Q

Macrophages

A

Ingest pathogens via endocytosis, digests them, and presents little pieces of them on major histocompatibility complex molecules, are one of the cell types that displays MHC-2 also (exogenous pathway), also secrete cytokines, derived from monocytes, resident populations called microglia in CNS, Langerhans cells in skin, osteoclasts in bone, etc, have special pattern recognition receptors

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22
Q

Cytokines

A

Secreted by macrophages, chemical substances that stimulate inflammation and recruit additional immune cells to the area

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23
Q

Major histocompatibility complex

A

MHC - proteins that present pathogens peptides (antigens) on, class I and class II exist, allows for antigens to be recognized by cells of the adaptive immune system

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24
Q

MHC Class I

A

Present in all nucleated cells and displays endogenous antigen to cytotoxic T cells, any cell in the body that has been infected with a virus/pathogen can display an antigen on MHC-1

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25
Q

Endogenous antigen

A

Proteins from within a cell, antigens presented on MHC-1

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26
Q

CD8+ cells

A

Cytotoxic T-cells, respond to antigens on MHC-1 (endogenous) and kill virally infected cells by injecting chemicals that promote apoptosis, most effective against viral (and intracellular bacterial or fungal) infections

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27
Q

MHC Class II

A

Present on professional antigen presenting cells and displays exogenous antigen to helper T cells after they phagocytize and process the pathogen from the outside environment, can result in activation of both innate and adaptive immune sys

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28
Q

Professional antigen presenting cells

A

Macrophages, dendritic cells, some B cells, and certain activated epithelial cells

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29
Q

Exogenous antigen

A

Proteins from outside the cell, present on MHC-II, can result in activation of both innate and adaptive immune sys

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30
Q

CD4+ cells

A

Helper T cells, respond to antigen on MHC II (exogenous antigens) and coordinate the rest of the immune system, secrete lymphokines, includes Th1 and Th2 cells, most effective against bacterial, fungal, and parasitic infections

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31
Q

Dendritic cells

A

Antigen-presenting cells in the skin

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32
Q

Natural killer cells

A

Attack (induces apoptosis in) cells not presenting MHC molecules (senses downregulation), including virally infected cells and cancer cells

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33
Q

Neutrophils

A

Ingest bacteria, particularly opsonized bacteria, use chemotaxis to follow bacteria, most populous leukocyte in the blood, dead collections forms pus during an infection

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34
Q

Opsonized bacteria

A

Those marked with antibodies from a B-cell

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35
Q

Eosinophils

A

Contain bright red-orange granules, used in allergic reactions and invasive parasitic infections, release histamine causing vasodilation and increased leakiness of blood vessels allowing more immune cells to move into tissues from bloodstream

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36
Q

Histamine

A

Triggers inflammatory response, released by eosinophils and basophils, results in vasodilation and increased leakiness of the blood vessels allowing additional immune cells to move out of the bloodstream and into the tissue

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37
Q

Basophils

A

Contain large purple granules, used in allergic reactions to release histamine, similar to mast cells

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38
Q

Mast cells

A

Related to basophils but have smaller granules and are found in the skin, release histamine in response to allergens

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39
Q

B-cells

A

Turn into plasma cells to produce antibodies as a part of adaptive immunity, created and mature in bone marrow, activated in spleen or lymph nodes and proliferate into plasma and memory B-cells, each can only produce one type of antibody at a time

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40
Q

Plasma cells

A

Produce antibodies after forming from B-cells as a part of adaptive immunity

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41
Q

Humoral immunity

A

Division of adaptive immunity that involves antibodies production by plasma cells (activated B-cells)

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42
Q

Cell-mediated immunity

A

aka cytotoxic immunity, division of adaptive immunity that is driven by T-cells because they coordinate the immune system and directly kill virally infected cells

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43
Q

Granules

A

Present in the cytoplasm of granulocytes, contain toxic enzymes and chemicals which can be released by exocytosis, particularly effective against bacterial, fungal, and parasitic pathogens

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44
Q

Hematopoietic stem cell

A

Precursor to all of hematopoiesis including all lymphoid stem cells and myeloid stem cells

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45
Q

Lymphoid stem cells

A

Precursor to B cells and T cells in hematopoiesis

46
Q

Myeloid stem cells

A

Precursor to leukocytes, erythrocytes, and platelets in hematopoiesis

47
Q

Granulocytes

A

Contain granules in cytoplasm, examples include neutrophils, eosinophils, and basophils

48
Q

Agranulocytes

A

Lack granules, include lymphocytes and monocytes

49
Q

Lymphocytes

A

Responsible for antibody productions, immune system modulation, and targeted killing of infected cells, includes T-cells and B-cells, both created in bone marrow

50
Q

Monocytes

A

Phagocytic cells in the bloodstream, become macrophages in tissues

51
Q

Classical pathway

A

Requires the binding of an antibody to a pathogen, actives complement system

52
Q

Alternative pathway

A

Does not require antibodies, activates complement system

53
Q

Antigen

A

Pathogenic peptide that can be presented on MHC, recognized by cells of the adaptive immune system, can be targeted by an antibody

54
Q

Pattern recognition receptors

A

PRR - present in macrophages and dendritic cells, able to recognize the category of the invader and allows fo the production of appropriate cytokines to recruit the right type of immune cells, one type is toll-like receptors

55
Q

Toll like receptors

A

TLR - type of pattern recognition receptor

56
Q

Chemotaxis

A

The movement of an organism according to chemical stimuli

57
Q

Pus

A

Formed because of dead neutrophil collections during an infection

58
Q

Inflammation

A

Mediated by histamine release, useful against extracellular pathogens such as bacteria, fungi, and parasites, causes vasodilation and increased leakiness of blood vessels allowing additional immune cells to move out of the bloodstream and into tissue

59
Q

Antibodies

A

aka immunoglobulins, produced by B-cells, target a particular antigen, contain two heavy chains and two light chains, have a constant region and variable region (whose tip is the antigen-binding region), types include circulating and cell surface antibodies

60
Q

Constant region

A

Region of an antibody, cells such as natural killer cells, macrophages, monocytes, and eosinophils have receptors for this reason and can initiate the complement cascade

61
Q

Variable region

A

Tip of which is the antigen-binding region, region of an antibody, contains specific polypeptide sequences that will bind only one specific antigenic sequence

62
Q

Antigen binding region

A

Part of the variable region of an antibody, undergoes hypermutation which activated

63
Q

Hypermutation

A

Occurs when the antigen binding region is activated, improves the specificity of the antibody products

64
Q

Isotypes

A

Includes IgM, IgD, IgG, IgE, IgA

65
Q

Opsonization

A

Marking pathogens for destruction, can be done by antibody

66
Q

Agglutination

A

Clumping of insoluble complexes that are ingested by phagocytes, can be done by antibodies

67
Q

Circulating antibodies

A

Can opsonize pathogens, cause agglutination, or neutralize pathogens by blocking their ability to invade tissues

68
Q

Cell-surface antibodies

A

Can activate immune cells or mediate allergic reactions when an antigen binds to the B-cell by triggering proliferation and formation of plasma and memory cells, on a mast cell, antigen binding to an antibody causes degranulation

69
Q

Memory B-cells

A

Lie in wait for a second exposure to a pathogen and can then mount a more rapid and vigorous immune response

70
Q

Secondary response

A

More rapid and vigorous immune response to second exposure of a pathogen because of memory B and T cells

71
Q

T-cells

A

Undergo maturation in the thymus through positive selection or negative selection, created in bone marrow

72
Q

Thymosin

A

A peptide hormone that promotes T-cell development, secreted by thymus cells

73
Q

Positive selection

A

Method of T-cell selection where only T-cells that can react to an antigen presented on MHC mature

74
Q

Negative selection

A

Method of T-cell maturation that causes apoptosis in self-reactive T-cells

75
Q

Lymphokines

A

Activate various arms of the immune defense, secreted by helper T-cells, recruit immune cells such as plasma cells, cytotoxic T cells and macrophages

76
Q

Th1 cells

A

Helper T cells that secrete interferon gamma

77
Q

Interferon gamma

A

Secreted by Th1 cells, activates macrophages

78
Q

Th2 cells

A

Helper T cells that activate B cells primarily during parasitic infections

79
Q

Suppressor T cells

A

aka regulatory T cells, tone down the immune response after an infection and promote self-tolerance, express CD4 but are differentiated by Foxp3

80
Q

Memory T cells

A

Lie in wait for a second exposure to a pathogen and can then mount a more rapid and vigorous immune response

81
Q

Autoimmune conditions

A

A self-antigen is identified as foreign and the immune system attacks the body’s own cells

82
Q

Allergic reactions

A

Nonthreatening exposures incite an inflammatory response

83
Q

Immunization

A

A method of inducting active immunity prior to exposure to a particular pathogen

84
Q

Active immunity

A

Activation of immune system B cells that produce antibodies to an antigen

85
Q

Passive immunity

A

Transfer of antibodies to an individual, transient because individual does only gets antibodies and not plasma cells, natural examples include transfer from mom to fetus/baby via placenta or breast milk

86
Q

Adaptive immune system divisions

A

Humoral and cell-mediated (cytotoxic) immunity

87
Q

Lymphocyte types

A

T-cells and B-cells

88
Q

Degranulation of mast cells

A

Occurs when an antigen binds to an antibody on a mast cell, exocytosis of granule contents which releases histamine and causes and inflammatory response

89
Q

Clonal selection

A

Mechanism where B-cells and T-cells that are able to bind an antigen with high affinity are the only ones to survive and proliferate

90
Q

Isotypes

A

The five different types of antibodies - IgM, IgD, IgG, IgE, IgA

91
Q

Isotype switching

A

Mechanism in which cells change which isotope of antibody they produce, stimulated by specific cytokines

92
Q

Naive B and T cells

A

Cells that are mature but have not yet been exposed to an antigen

93
Q

Primary response

A

The initial immune response to a pathogen, takes 7-10 days approximately

94
Q

Human immunodeficiency virus

A

HIV - loss of helper T-cells which prevent the immune system from mounting an adequate response to an infection

95
Q

Acquired immunodeficiency syndrome

A

AIDS - advanced HIV infection

96
Q

Self tolerance

A

When suppressor or regulatory T cells tone down the immune response (including turning off self reactive lymphocytes) to prevent autoimmune disease

97
Q

Types of infectious pathogens

A

Bacteria, virus, fungi, parasites, prions

98
Q

Self antigens

A

Proteins and carbohydrates present on the surface of every cell in the body

99
Q

Autoimmunity

A

When the immune system fails to make the distinction between self and foreign and attacks cells expressing particular self antigens

100
Q

Hypersensitivity reactions

A

Family of immune reactions that includes autoimmunity and allergies

101
Q

Treatment of autoimmune diseases

A

Administration of glucocorticoids because they have potent immunosuppressive qualities

102
Q

Autoimmune prevention

A

Negative selection of T-cells and eliminations of B-cells that respond to self antigens prior to leaving bone marrow

103
Q

Lymphatic system

A

Circulatory system that consists of one-way vessels with intermittent lymph nodes, equalizes fluid distribution, transports fats and fat soluble compounds in chylomicrons, and provides sites for mounting immune responses

104
Q

Thoracic duct

A

In posterior chest, connects the lymphatic system to the cardiovascular system

105
Q

Chylomicrons

A

What fat is packaged into by intestinal mucosal cells in the small intestine

106
Q

Lymph

A

Lymphatic fluid

107
Q

Lymph nodes

A

Small, bean-shaped structures along the lymphatic vessels, contain a lymphatic channel, artery, and vein, provides a space for immune system cells to be exposed to possible pathogens

108
Q

Edema

A

Swelling due to fluid collecting in tissue when the lymphatics are overwhelmed

109
Q

Lymphatic system fluid equalization

A

Lymphatic system returns fluid to bloodstream that was taken out because of hydrostatic forces and not pulled back in because net osmotic pressure puling back into the venule end of the capillaries is slightly less than thehydrostatic pressure

110
Q

Lacteals

A

Small lymphatic vessels located at the center of each chills in the small intestine, where fats packaged into chylomicrons enter from transport

111
Q

Chyle

A

Lymphatic fluid carrying many chylomicrons with a milky white appearance

112
Q

Germinal centers

A

Location in the lymph nodes where B-cells proliferate and mature

MCAT (67 decks)

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