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MCAT Biology > Chapter 8: The Immune System > Flashcards

Chapter 8: The Immune System Flashcards

1
Q

________ immunity is composed of defenses that are always active against infection, but lack the ability to target specific invaders.

A

innate

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2
Q

Innate immunity is also known as ____________ immunity.

A

nonspecific

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3
Q

____________ or ____________ immunity refers to the defenses that target a specific pathogen.

A

adaptive, specific

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4
Q

Which type of immunity is slower to act but maintains immunological memory to mount a faster attack in subsequent infections?

A

Adaptive immunity

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5
Q

What produces all of the leukocytes? What is this process called?

A

bone marrow; hematopoiesis

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6
Q

The spleen is a location of blood storage and activation of ____-________, which turn into ____________ cells to produce antibodies as part of adaptive immunity.

A

B-cells; plasma

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7
Q

When B-cells leave the bone marrow, they are considered mature but naive. Why?

A

They have not yet been exposed to an antigen.

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8
Q

Because B-cells dissolve and act in the blood (rather than within cells), this division of adaptive immunity is called ____________ immunity.

A

humoral

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9
Q

____-________, another class of adaptive immune cells, mature in the thymus, a small gland just in front of the pericardium, the sac that protects the heart.

A

T-cells

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10
Q

T-cells are the agents of ________-____________ immunity, because they coordinate the immune system and directly kill virally infected cells.

A

cell-mediated

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11
Q

________ ________, a major component of the lymphatic system, provide a place for immune cells to communicate and mount an attack. B-cells can be activated here as well.

A

lymph nodes

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12
Q

____-________ ________ tissue, which are found in close proximity to the digestive system, can be a site of potential invasion by pathogens. This could include the ________ and ____________ in the head, ________ ________ in the small intestine, and lymphoid aggregates in the ____________.

A

gut-associated lymphoid tissue (GALT); tonsils/adenoids, Peyer’s patches, appendix

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13
Q

________ ________ is the site of immune cell production.

A

Bone marrow

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14
Q

The ________ is the site of T-cell maturation.

A

thymus

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15
Q

The ________ acts as a storage area for WBCs and platelets, a recycling center for RBCs, and a filter of blood and lymph for the immune system.

A

spleen

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16
Q

Granulocytes and agranulocystes are the 2 groups of leukocytes. What is their precursor?

A

hematopoietic stem cells

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17
Q

What are the 3 types of granulocytes?

A
  1. neutrophils
  2. eosinophils
  3. basophils
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18
Q

What are the 2 types of leukocytes?

A

granulocytes and agranulocytes

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19
Q

Agranulocytes include the ____________, which are responsible for antibody production, immune system modulation, and targeted killing of infected cells, as well as ____________, which are phagocytic cells in the bloodstream.

A

lymphocytes, monocytes

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20
Q

Monocytes become ____________ in tissues.

A

macrophages

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21
Q

What are macrophages in the CNS called?

A

microglia

1

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22
Q

What are macrophages in the skin called?

A

Langerhans cells

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23
Q

What are macrophages in bone called?

A

osteoclasts

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24
Q

The specific immune system can be divided into what two types of immunity?

A

humoral and cell-mediated immunity

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25
Q

What drives humoral immunity? Cell-mediated immunity?

A

B-cells and antibodies; T-cells

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26
Q

What is innate immunity also known as?

A

nonspecific immune response

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27
Q

What is adaptive immunity known as ?

A

specific immune response

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28
Q

The ____________ system consists of a number of proteins in the blood that act as a nonspecific defense against bacteria.

A

complement

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29
Q

Complement can be activated through what 2 pathways?

A

classical or alternative

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30
Q

What is the classical pathway for the complement system?

A

Requires the binding of an antibody to a pathogen

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31
Q

What is the alternative pathway to the complement system?

A

does not require antibodies; punches holes in bacterial cell walls

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32
Q

Cells that have been infected with viruses also produce ____________, which are proteins that prevent viral replication and dispersion.

A

interferons

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33
Q

Interferons upregulate which molecules? What does this cause?

A

MHC class I and class II molecules; results in increased antigen presentation and better detection of the infected cells by the immune system

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34
Q

What do interferons do to nearby cells?

A

Cause them to decrease production of both viral and cellular proteins; decreases permeability

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35
Q

What is responsible for many flu-like symptoms during viral infection?

A

interferons

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36
Q

Where are macrophages derived from?

A

blood-borne monocytes

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37
Q

Macrophages can become a ____________ population within a tissue.

A

resident

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38
Q

When a bacterial invader enters a tissue, the macrophages become activated. What 3 things does an activated macrophage do?

A
  1. Phagocytizes the invader
  2. Digests the invader with enzymes
  3. Presents pieces of the invader (mostly peptides) to other cells
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39
Q

What protein does a macrophage use to present the invader to other cells?

A

It uses the major histocompatibility complex (MHC).

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40
Q

MHC binds to a pathogenic peptide, known as an ____________, and carries it to the cell surface, where it can be recognized by cells of the adaptive immune system.

A

antigen

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41
Q

Macrophages also release ____________, which are chemical substances that stimulate inflammation and recruit additional immune cells to the area.

A

cytokines

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42
Q

All nucleated cells in the body display MHC Class ____ molecules. Any protein produced within a cell can be loaded onto MHC-I and presented on the ________ of a cell.

A

I; surface

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43
Q

The MHC-I pathway is often called the ____________ pathway because it binds antigens that come from inside the cell.

A

endogenous

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44
Q

Cells that have been invaded by intracellular pathogens can then be killed by a certain group of ____-________ to prevent infection of other cells.

A

T-cells

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45
Q

MHC class ____ molecules are mainly displayed by professional ________-____________ cells like macrophages.

A

II; antigen-presenting

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46
Q

____________ pick up pathogens from the environment, process them, and then present them on ________-________ cells.

A

macrophages; MHC-II

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47
Q

An ____________ is a substance that can be targeted by an antibody.

A

antigen

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48
Q

Because these antigens originate from outside the cell, the MHC-II pathway is often called the ____________ pathway.

A

exogenous

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49
Q

Professional antigen-presenting cells include macrophages, ________ cells in the skin, some B-cells, and certain activated epithelial cells.

A

dendritic

50
Q

Macrophages and dendritic cells also have special receptors known as ________ ____________ receptors. These are capable of recognizing molecules frequently found in pathogens.

A

pattern recognition

51
Q

____-____ receptors are a common type of pattern recognition receptors.

A

toll-like

52
Q

Pattern recognition receptors allow the production of appropriate ____________ to recruit the right type of immune cells.

A

cytokines

53
Q

Some viruses cause downregulation of MHC molecules, what does this do for T-cells?

A

Makes it harder for them to recognize the presence of infection

54
Q

____________ ____________ cells are a type of nonspecific lymphocyte that can detect the downregulation of MHC and induce apoptosis in these virally infected cells.

A

natural killer

55
Q

____________ are the most populous leukocyte in blood and are short-lived.

A

neutrophils

56
Q

Neutrophils are ____________, like macrophages, and target bacteria. They follow bacteria using ____________ - the movement of an organism according to chemical stimuli.

A

phagocytic; chemotaxis

57
Q

Neutrophils can also detect bacteria once they have been ____________ (marked with an antibody from a B-cell).

A

opsonized

58
Q

Dead neutrophil collections are responsible for the formation of ____ during an infection.

A

pus

59
Q

____________ contain bright red-orange granules and are primarily involved in allergic reactions and invasive parasitic infections.

A

eosinophils

60
Q

Upon activation, eosinophils release large amounts of ____________, an inflammatory mediator.

A

histamine

61
Q

Histamine results in vasodilation and increased leakiness of blood vessels. What does that do?

A

Allows additional immune cells (especially macrophages and neutrophils) to move out of the bloodstream and into tissue

62
Q

____________ contain large purple granules and are involved in allergic responses. They are the least populous under normal conditions.

A

basophils

63
Q

________ cells are closely related to basophils, but have smaller granules and exist in the tissues, mucosa, and epithelium.

A

mast cells

64
Q

What are the two divisions of the adaptive immune system?

A

humoral immunity and cell-mediated (cytotoxic) immunity

65
Q

What are the 2 main types of lymphocytes?

A

B-cells and T-cells

66
Q

B-cells mature in the ____________ and ________. T-cells mature in the ____________.

A

bone marrow and spleen; thymus

67
Q

Humoral immunity involves the production of ____________, and it may take as long as ________ to become fully effective after initial infection.

A

antibodies; week

68
Q

Antibodies are specific to the ____________ of the invading microbe. Antibodies are produced by ____-cells, which are lymphocytes that originate and mature in the bone marrow and are activated in the ________ and ________ ________.

A

antigen; B; spleen and lymph nodes

69
Q

Antibodies are also called ________________.

A

immunoglobulins (Ig)

70
Q

When an antibody binds to an antigen, the response depends on what?

A

THe location

71
Q

For antibodies secreted into body fluids, what are the 3 main possibilities?

A
  1. Antibody attracts other leukocytes to phagocytize
  2. May cause pathogens to agglutinate to be phagocytized
  3. antibodies can block ability of pathogen to invade tissues (neutralize)
72
Q

For cell-surface antibodies, the binding of antigen to a B-cell causes what?

A

Activation of the cell, resulting in its proliferation and formation of plasma and memory cells

73
Q

When an antigen binds to antibodies on the surface of a mast cell, it causes ____________, releasing ____________ and causing an inflammatory allergic reaction.

A

degranulation; histamine

74
Q

What is degranulation?

A

exocytosis of granule contents

75
Q

Antibodies are Y-shaped molecules that are made up of two identical ________ chains and two identical ________ chains.

A

heavy; light

76
Q

What holds heavy and light chains together?

A

disulfide linkages and non-covalent interactions

77
Q

Each antibody has an ________-________ region at the end of which is called the ________ region (domain), at the tips of the Y.

A

antigen-binding; variable

78
Q

Within the variable region, there are specific polypeptide sequences that will bind how many antigenic sequences?

A

Only one

79
Q

Each B-cell undergoes ____________ of its antigen-binding region, trying to find the best match for the antigen.

A

hypermutation

80
Q

Only those B-cells that can bind the antigen with high affinity survive, providing a mechanism for generating specificity called ________ ____________.

A

clonal selection

81
Q

The remaining part of the antibody molecule is known as the ________ region (domain). This is where receptors are that can initiate the ____________ cascade.

A

constant; complement

82
Q

How many different isotypes of antibodies are there?

A

5

83
Q

Cells can change which isotype of antibody they produce when stimulated by specific cytokines in a process called what?

A

isotype switching

84
Q

________ B-cells that have not yet been exposed to an antigen wait where for their particular antigen to come along?

A

naive; lymph nodes

85
Q

Upon exposure to the correct antigen, a B-cell will proliferate and produce two types of daughter cells. What are they?

A

Plasma cells and memory B-cells

86
Q

________ cells produce large amounts of antibodies, whereas ________ ____-________ stay in the lymph node, awaiting reexposure to the same antigen.

A

plasma; memory B

87
Q

The initial activation of plasma and memory B-cells takes 7-10 days and is known as the ____________ response.

A

primary

88
Q

Plasma cells eventually die, but the memory cells may last the lifetime of the organism. If the same microbe is encountered, the ________ cells proliferate and differentiate into plasma cells to produce specific antibodies. This is known as the ________ response.

A

memory; secondary

89
Q

Cell-mediated immunity involves which cells?

A

T-cells

90
Q

T-cells mature in the ________, where they undergo both positive and negative selection.

A

thymus

91
Q

________ selection refers to allowing only the maturation of cells that can respond to the presentation of antigen on MHC (cells that cannot respond to MHC undergo apoptosis because they will not be able to respond in the periphery).

A

positive

92
Q

____________ selection refers to causing apoptosis in cells that are self-reactive (activated by proteins produced by the organism itself).

A

negative

93
Q

The maturation of T-cells is facilitated by ____________, a peptide hormone secreted by thymic cells.

A

thymosin

94
Q

Once the T-cell has left the thymus, it is mature but naive. When it is exposed to antigen, it will undergo clonal selection so that only those with the highest ____________ for a given antigen proliferate.

A

affinity

95
Q

What are the 3 types of T-cells?

A
  1. Helper T-cells
  2. Suppressor T-cells
  3. Killer (cytotoxic) T-cells
96
Q

Helper T-cells are also called ________ T-cells, and they coordinate the immune response by secreting chemicals known as ____________.

A

CD4+; lymphokines

97
Q

____________ can recruit other immune cells and increase their activity.

A

Lymphokines

98
Q

CD4+ T-cells respond to antigens presented on ____________ molecules.

A

MHC-II

99
Q

Cytotoxic T-cells, also called ____ T-cells, are capable of directly killing virally infected cells by injecting toxic chemicals that promote ____________ into the infected cell.

A

CD8+, apoptosis

100
Q

CD8+ T-cells respond to antigens presented on ________ molecules.

A

MHC-I

101
Q

Since MHC-I presents endogenous antigens, Cd8+ T-cells are most effective against what infections?

A

viral (and intracellular bacterial or fungal)

102
Q

Suppressor or ________ T-cells also express ____, but can be differentiated from helper T-cells because they also express a protein called ________.

A

regulatory; CD4; Foxp3

103
Q

Regulatory T-cells turn off self-reactive lymphocytes to prevent autoimmune diseases; this is called what?

A

self-tolerance

104
Q

________ T-cells can also be generated, and they lie in wait until the next exposure to the same antigen.

A

memory

105
Q

In bacterial (extracellular) pathogen infections, ____________ will first engulf bacteria and release inflammatory mediators.

A

macrophages

106
Q

____________ attract inflammatory cells, which activate ________ cells and cause degranulation, which results in ____________ release and increased leakiness of the capillaries.

A

cytokines; mast; histamine

107
Q

____________ cell leave affected tissue and travel to the nearest lymph node, where it presents the antigen to ____-________.

A

dendritic; B-cells

108
Q

____________ cells also present the antigen to ____-cells and activate the ________ T-cells.

A

dendritic, T; CD4+

109
Q

For virally infected cells, they present intracellualr proteins on their surface in conjunction with ________.

A

MHC-I

110
Q

What T-cells recognize the MHC-I?

A

CD8+

111
Q

________-________ are the proteins and carbs present on the surface of every cell of the body. They signal to immune cells that a cell is not foreign and should not be attack.

A

self-antigens

112
Q

Part of preventing autoimmune reactions involves ____________ of T-cells that respond to self-antigens. This is called ____________ selection.

A

elimination; neagtive

113
Q

In ________ immunity, the immune system is stimulated to produce antibodies against a specific pathogen.

A

active

114
Q

________ immunity results from the transfer of antibodies to an individual.

A

passive

e.g. fetal

115
Q

The lymphatic system is made up of one-way vessels that carry ________ and most join to form a large ____________ duct in the posterior chest, which then delivers fluid into the left ____________ vein near the heart.

A

lymph; thoracic; subclavian

116
Q

________ ________ are small, bean-shaped structures along lymphatic vessels. They contain a lymphatic ________, an artery, and vein.

A

lymph nodes; channel

117
Q

The ________ pressure of blood draws water back into the vessel at the ________ end, once ____________ pressure has decreased.

A

oncotic; venule; hydrostatic

118
Q

Because the net pressure drawing fluid in at the venule end is slightly less than the net pressure pushing fluid out at the arterial end, a small amount of fluid remains in tissues. ________ vessels drain these tissues and return the fluid to the bloodstream.

A

Lymphatic

119
Q

____________, small lymphatic vessels, are located at the center of each villus in the small intesetine. ________, packaged into chylomicrons by intestinal mucosal cells, enter the lacteal for transport. Lymphatic fluid carrying many chylomicrons takes on a milky white appearance and is called ________.

A

Lacteals; fats; chyle

120
Q

Lymph nodes are a place for which cells to interact? B-cells proliferate and mature in the lymph nodes in collections called ____________ centers.

A

APC and lymphocytes; germinal

MCAT Biology (12 decks)

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