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MCAT Biological Sciences > Chapter 8- The Immune System > Flashcards

Chapter 8- The Immune System Flashcards

1
Q

2 divisions of immune system

A
  1. innate (nonspecific)- always active
  2. adaptive (specific)- defenses that target a specific pathogen, slower to act but has memory of infections and can fight them off faster if exposed again
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2
Q

spleen

A

location of blood storage and activation of B-cells, which turn into plasma cells to produce antibodies as part of adaptive immunity

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3
Q

humoral immunity

A

antibodies dissolve and act in blood instead of within cells

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4
Q

T-cells

A

agents of cell-mediated immunity b/c they coordinate the immune system and directly kill virally infected cells

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5
Q

lymph nodes

A

provide a place for immune cells to communicate and mount an attack. B-cells can be activated here as well.

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6
Q

gut-associated lymphoid tissue (GALT)

A

immune tissue found close to digestive system (site of potential invasion-ex: mouth). this tissue includes tonsils and adenoids in the head, peyer’s patches in small intestine, and lymphoid aggregates in the appendix.

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7
Q

4 organs of immune system

A
  1. lymph nodes (filter lymph and where immune responses can be mounted)
  2. bone marrow (site of immune cell production)
  3. thymus (site of T-cell maturation)
  4. spleen (storage for blood and lymph, immune response can also be mounted here)
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8
Q

granules

A

contain toxic enzymes and chemicals which can be released by exocytosis (particularly effective against bacterial, fungal, and parasitic pathogens)

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9
Q

hematopoietic stem cells

A

stem cells that create pretty much any cell in blood (red/white/platelets)

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10
Q

lymphocytes

A

antibody production/ immune modulation/ targeted killing of infected cells

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11
Q

2 types of specific (adaptive) immunity

A
  1. humoral (B-cells and antibodies)

2. cell-mediated (T-cells)

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12
Q

integument

A

skin, first line of defense

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13
Q

defensins

A

antibacterial enzymes found on skin

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14
Q

lysozyme

A

nonspecific bacterial enzyme secreted in tears and saliva

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15
Q

how does the GI-tract help with nonspecific immunity?

A
  1. stomach- secretes acid that usually kills most pathogens

2. gut- colonized by bacteria

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16
Q

complement system

A

many proteins in blood that act as nonspecific defense against bacteria. these punch holes in cell walls of bacteria

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17
Q

2 pathways to activate complement system?

A
  1. classical- binding of antibody to pathogen

2. alternative- no antibody required

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18
Q

interferons

A

produced by cells that have been infected with viruses. these are proteins that prevent viral replication and dispersion.

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19
Q

when bacteria enters a tissue, what gets activated?

A

macrophages (first phagocytize then digests invader)

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20
Q

major histocompatibility complex (MHC)

A

macrophages show little proteins of pathogen to this, so it can bind to it and brings it to the cells surface where it can be recognized by the adaptive immune system.

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21
Q

what do macrophages release?

A

cytokines- chemical substances that stimulate inflammation and recruit additional immune cells to the area.

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22
Q

2 classes of MHCs

A

Class I: in all nucleated cells and presents endogenous antigens
Class II: in antigen-presenting cells and presents exogenous antigens

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23
Q

what happens to cells that have been invaded by intracellular pathogens?

A

can be killed by a certain group of T-cells (cytotoxic T-lymphocytes) to prevent infection of other cells

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24
Q

antigen

A

substance (usually a pathogenic protein) that can be targeted by an antibody

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25
Q

examples of professional antigen-presenting cells

A

macrophages, dendritic cells, some B-cells, and some activated epithelial cells.

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26
Q

Pattern Recognition Receptors (PRR)

A

special receptors on macrophages and dendritic cells (ex: toll-like receptors-TLR) able to recognize category of invader which allows for appropriate cytokines to recruit the right type of immune cells.

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27
Q

Natural killer cells

A
  • destroys the body’s own cells that have become infected with pathogens
  • goes after cancer cells
  • monitor expression of MHC molecules on surface of cells
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28
Q

3 types of granulocytes

A
  1. neutrophils
  2. eosinophils
  3. basophils
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29
Q

neutrophils

A

short-lived. phagocytic and target bacteria. follow bacteria using chemotaxis and can follow opsonized (marked with antibody from B-cell) bacteria

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30
Q

pus formation

A

dead neutrophil collections

31
Q

eosinophils

A

bright red-orange granules. allergic reactions and invasive parasitic infections. release large amounts of histamine (inflammatory mediator) once activated which results in vasodilation.

32
Q

basophils

A

large purple granules. allergic responses. mast cells are closely related, but have smaller granules and exist in the tissues, mucosa, and epithelium. both release histamine

33
Q

dendritic cell

A

presents antigens-fragments of protein or other molecules from pathogens or cancer cells- to adaptive immune cells, inducing the cells to attack bearers of displayed antigens

34
Q

B-cell

A

antigens stimulate this cell to divide and produce antibodies that neutralize invaders or tag them for killing

35
Q

T-cell

A

killer T-cell destroys an infected cell in which it detects the presence of antigens. other T-cells- such as helper and regulatory types- coordinate the immune response

36
Q

what activates natural killer cells?

A

cells that do not present MHC (virally infected and cancer cells)

37
Q

B and T-cell creation and maturity and activation locations

A

B-cells (bone marrow, bone marrow, spleen/ lymph nodes)

T-cells (bone marrow, thymus, N/A)

38
Q

humoral immunity

A

production of antibodies. may take up to a week to become fully effective after initial infection. antibodies are produced by B-cells

39
Q

antibodies and the 5 subtypes

A

aka. immunoglobulins. (IgM, IgD, IgG, IgE, and IgA). Cells change whch they produce when stimulated by specific cytokines which is called isotype switching.

40
Q

Opsonization

A

When an antibody binds to an antigen and the antibody attracts other leukocytes to phagocytize those antigens immediately

41
Q

antibody molecule structure

A

Y-shaped made up of 2 identical heavy and 2 identical light chains.

42
Q

Name one thing an antibody can you do after binding to an antigen

A

The antibodies can block the ability of a pathogen to invade tissues. essentially neutralizing it

43
Q

Degranulation

A

This occurs when an antigen binds to an anti-body on the surface of a mast cell and it allows for the release of histamine and causing an inflammatory allergic reaction

44
Q

degranulation

A

exocytosis of granule contents

45
Q

antibody molecule structure

A

Y-shaped made up of 2 identical heavy and 2 identical light chains

46
Q

antigen-binding region

A

at the end of each variable region (domain), at the tips of the Y. this is the site where one specific antigenic sequence can bind. each B-cell undergoes hypermutation of this region trying to find the best match for the antigen.

47
Q

clonal selection

A

only B-cells that can bind the antigen with high affinity survive, generates specificity

48
Q

constant region (domain)

A

cells such as NKC, macrophages, monocytes, and eosinophils have receptors for this region and can initiate the complement cascade.

49
Q

naive B-cells

A

B-cells that have not been exposed to an antigen yet wait in the lymph nodes for their particular antigen

50
Q

Plasma cells

A

produce large amounts of antibodies. will eventually die

51
Q

3 types of T-cells

A
  1. Helper T-cells (CD4+)
  2. Cytotoxic T-cells (CD8+)
  3. Suppressor/ regulatory T-cells
52
Q

lymphokines

A

capable of recruiting other immune cells (plasma, cytotoxic, and macrophages) and increasing their activity. these are lost in HIV/AIDS

53
Q

what happens to T-cells as they mature in the thymus

A
  1. positive selection (maturing only cells that can respond to the presentation of the antigen on MHC)
  2. negative selection (causing apoptosis in cells that do not respond to presentation of MHC antigen)
54
Q

thymosin

A

facilitates maturation of T-cells. a peptide hormone secreted by thymic cells.

55
Q

3 types of T-cells

A
  1. Helper T-cells aka. CD4+ T-cells (coordinate the immune response by secreting chemicals known as lymphokines)
56
Q

lymphokines

A

capable of recruiting other immune cells (plasma, cytotoxic, and macrophages) and increasing their activity

57
Q

Helper T-cells

A

aka. CD4+ T-cells. coordinate the immune response by secreting chemicals known as lymphokines. respond to antigens presented on MHC-II molecules. most effective against bacterial, fungal, and parasitic infections.

58
Q

5 types of infectious pathogens

A

bacteria, viruses, fungi, parasites, and prions (no immune defense for prions)

59
Q

Suppressor/ Regulatory T-cells

A

express CD4 but also have Foxp3 protein. help tone down immune response once infection has been contained. self-tolerance

60
Q

self-tolerance

A

turn off self-reactive lymphocytes to prevent autoimmune diseases

61
Q

self-antigens

A

proteins and carbohydrates on the surface of every cell of the body.

62
Q

5 types of infectious pathogens

A

bacteria, viruses, fungi, parasites, and prions

63
Q

viral infections are…

A

intracellular pathogens

64
Q

bacterial infections are…

A

extracelluar pathogens

65
Q

self-antigens

A

proteins and carbohydrates on the surface of every cell of the body.

66
Q

allergies

A

when immune system misidentifies a foreign antigen as dangerous when its not so its hypersensitive to these antigens and becomes overactive in their presence.

67
Q

lymphatic system function

A

equalizing fluid distribution, transportation of biomolecules (chylomicrons from small intestine to circulatory system), and immunity (B-cells proliferate and mature in lymph nodes in collections called germinal centers)

68
Q

active immunity

A

immune system is stimulated to produce antibodies against a specific pathogen

69
Q

passive immunity

A

transfer of antibodies to an individual (ex: fetus)

70
Q

structure of lymphatic system

A

type of circulatory system. one-way vessels that become larger as they move toward the center of the body. vessels carry lymph and join to comprise a large thoracic duct in the posterior chest (delivers fluid into the left subclavian vein near the heart)
lymph nodes: contain lymphatic channel/ artery/ vein. provide a space for the cells of the immune system to be exposed to possible pathogens.

71
Q

lymphatic system function

A

equalizing fluid distribution, transportation of biomolecules

72
Q

edema

A

swelling due to fluid collecting in tissue. occurs when lymphatics are overwhelmed

73
Q

what structure is responsible for returning materials from lymphatic circulation to the cardiovascular system?

A

thoracic duct carries lymphatic fluid into left subclavian vein

74
Q

platelet

A

fragments of megakaryocytes

MCAT Biological Sciences (12 decks)

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