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Immunology Midterm 1 > immune system > Flashcards

immune system Flashcards

1
Q

what is immunology

A

the study of the physiological mechanisms that animals use to defend themselves from invasion by other organisms

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2
Q

what protects us from invading organisms

A

the immune system

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3
Q

what is the purpose of the immune system

A

the immune system recognizes and destroys things that are dangerous to our bodies

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4
Q

what can dangers to our immune system come from

A

exogenous sources or endogenous sources

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5
Q

what is an exogenous source

A

a danger that originates outside of the body
ex. viruses, bacteria, parasites, fungi

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6
Q

what is an endogenous source

A

a danger that originates inside of the body
ex. damaged cell, cancerous cell

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7
Q

what are the major categories of human pathogens

A

viruses (cold, flu, measles, ebola, etc),
bacteria (TB, lyme disease, pneumonia), fungi (ringworm, meningitis, etc), parasites (malaria, amoebic colitis)

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8
Q

what is a tumour

A

a group of cells that have lost control of their cell cycle and divide uncontrollably

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9
Q

what is immunity

A

the state of protection against foreign pathogens or substance (antigens)

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10
Q

what is an antigen

A

anything that the body makes an immune response against

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11
Q

what are examples of an antigen

A

pathogens, allergens, toxins, red blood cell antigens

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12
Q

what happens when you’re exposed to the same pathogen for a second time

A

immunity
- reduced or no symptoms

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13
Q

what two immune responses work together to eliminate pathogens or tumours

A

innate and adaptive

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14
Q

what are innate immune responses found in

A

all organisms
- animals, plants, bacteria

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15
Q

what happens to your innate immune response after repeat exposure to the same pathogen

A

responses do not change after repeated exposure to the same pathogen

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16
Q

what does it mean in the innate immune system to have non-specific responses

A

activation by one pathogen can protect against other pathogens

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17
Q

what are adaptive immune responses found in

A

only present in animals with a backbone and jaw
- fish, reptiles, birds, mammals

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18
Q

what are the three characteristics in adaptive immune responses

A

specificity: incredibly specific, combats one specific pathogen

diversity: mounts an immune response to almost anything

memory: the next time your adaptive immune response encounters that same pathogen, it will respond faster and stronger

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19
Q

what part of the adaptive immune response do vaccines target

A

memory

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20
Q

what barriers does the body have to protect against pathogens

A
  • mucosa (lungs, GI tract, genitourinary system
  • skin
  • epithelial cell barriers that line the body’s surfaces
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21
Q

how do epithelial cells create their barrier

A

using tight junctions

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22
Q

in epithelial tight junctions, nothing can move from ______ to _______

A

nothing can move from the apical (faces the environment) to the basal side of the epithelial layer

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23
Q

what is a ciliated epithelial cell

A

a barrier defense that lines airways and can sweep inhaled pathogens up and out of the lung
- mucociliary escalator

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24
Q

what are goblet cells

A

a barrier defense in mucosal surfaces secret mucous that contains glycoproteins and enzymes to bind to/digest pathogen surfaces
ex. lysozyme and gram-positive bacteria

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25
Q

what are surfactant-producing cells

A

a barrier defense in the lung and GI tract that secret surfactant proteins that bind to pathogen cell walls and facilitate their destruction by immune cells

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26
Q

what are mucosal epithelial cells

A

barrier defense that transports antibodies from inside the body to the mucosal surface to enable the antibody to bind pathogens

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27
Q

what do surfactant proteins do

A
  • surfactant protein A and D (SP-A and SP-D)
  • bind bacteria
  • cause lysis directly
    OR
  • enhance the uptake of bacteria by immune cells
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28
Q

How do humans make their own antibiotics and what are they called

A
  • called alpha and beta defensins
  • they are antimicrobial peptides
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29
Q

what are human made antibiotics produced by

A

epithelial cells and neutrophils

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30
Q

how do human made antibiotics work

A

they insert themselves into pathogen cell walls, disturbing their membranes and causing pore formation
- bacterial cell walls are more negatively charged than host cell walls, attract positively charged AMPs

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31
Q

what else are human made antibiotics made by

A

all vertebrates, invertebrates, plants and some fungi

32
Q

what happens if our barriers are crossed

A

our innate immune response steps up

33
Q

how do we compromise our barriers

A

scraped knees, cooking accidents

34
Q

what is an example of how pathogens cross barriers

A

influenza virus makes neuraminidase, an enzyme that breaks down mucous

35
Q

are innate responses highly conserved

A

yes
- toll receptors in fruit flies and nematode worms are very similar to toll-like receptors found in humans

36
Q

innate immune cells

A
  • white blood cells are immune cells
  • also called leukocytes (or leucocytes)
  • all leukocytes are innate immune cells with the exception of lymphocytes (B and T cells)
37
Q

what do innate receptors bind to

A

the structures produced pathogens or released by damaged cells
- PRRs; pattern recognition receptors

38
Q

what is DAMP

A

danger associated molecular pattern
- molecules which are usually inside a cell but are detected outside the cell
- ex. extracellular ATP, heat shock proteins

39
Q

what is PAMP

A

pathogen associated molecular pattern
- molecules produced by pathogens
- ex. lipopolysaccharide, double-stranded RNA

40
Q

what happens to successful pathogens

A

they will have mechanism to evade or shut down innate immune responses

41
Q

what is the flow of pathogens in adaptive immunity

A

nick face when shaving –> barriers (skin, mucous) –> more innate immune responses (phagocytes, complement, etc) –> usually sufficient to prevent infection, but sometimes is not –> activate adaptive immunity

42
Q

what are adaptive immune responses mediated by

A
  • T cells and B cells
43
Q

diversity in adaptive immune responses

A

immune response can be mounted against almost anything
- ex. proteins, sugars, nucleic acids, fats

44
Q

specificity in adaptive immune responses

A

immune response can differentiate between very similar molecules
- ex. can tell the difference between the same protein with or without a single phosphate group

45
Q

memory in adaptive immune response

A

responds to a reinfection faster and stronger than a first exposure (escalating response)
- basis for vaccination

46
Q

how is the adaptive immune response so diverse

A
  • lymphocytes make rearranged receptors that are highly variable and behind a unique ligand
  • T cell antigen receptors and B cell antigen receptors that are present in your body right now are your unique ‘repertoire’
47
Q

what is a ligand

A

a substrate that binds to a receptor

48
Q

how is the adaptive immune response so specific

A
  • depending on the receptors sequence it will bind different ligands
  • these ligands are called antigens = antibody generator
49
Q

what does clonal mean in regards to adaptive immunity

A
  • lymphocytes are clonal
  • repertoire of lymphocytes contain single B and T cells with unique receptors
  • one cell wouldn’t be enough to fight off a pathogen
  • once it finds a match that B or T cell undergoes rapid mitosis to make lots of daughter cells (clones)
50
Q

what are the two phases of adaptive immunity

A

primary immune response and secondary immune response

51
Q

what is the primary immune response in adaptive immunity

A

the first time you are infected with a pathogen

52
Q

what is the secondary immune response in adaptive immunity

A

subsequent re-infection with the same pathogen

53
Q

a lymphocyte that has never been activated is referred to as ____

A

naive

54
Q

where are naive T cells

A

they circulate through the bloodstream and move through the secondary lymph organs (spleen and lymph nodes)

55
Q

where are naive B cells

A

they reside in B cell areas of lymph nodes

56
Q

what are the two examples of T cells

A
  • CD4+ helper T cells
  • CD8+ killer (cytotoxic) T cells
57
Q

what do CD4+ helper T cells do

A
  • help with shaping the immune response
  • help activates B cells
58
Q

what do CD8+ killer (cytotoxic) T cells do

A

move to the infected tissue and kill infected cells or cancerous cells

59
Q

what are activated B cells called

A

plasma cells

60
Q

what do activated B cells do

A
  • stay in the lymph node and differentiate into plasma cells
  • antibody producing machines
  • secret antibodies that are their BCRs but soluble
  • antibodies enter the blood stream –> infected tissue
61
Q

what is the duration of the primary immune response

A
  • 7 to 10 days for a primary immune response to mount
  • this includes cellular activation, proliferation and differentiation
62
Q

after T calls and antibodies stop the infection, what percent of activated B and T cells die and by what

A

after the T cells and antibodies stop the infection, 90 - 95% of activated B and T cells will die by apoptosis

63
Q

what percent of activated B and T cells remain after infection is stopped, and what do they remain as

A

5 - 10 % remain as memory B and T cells

64
Q

where are Central memory T cells (Tcm)

A
  • circulate throughout the whole body
  • found in blood and secondary lymph nodes
65
Q

where are effector memory T cells (Tem)

A
  • circulate the originally infected tissue and its draining lymph node
  • but not the blood
66
Q

where are tissue resident memory T cells (Trm)

A

stay in the tissue, particularly skin and mucosal surfaces (lung, GI tract, vagina)
- but not in secondary lymphoid organs or blood

67
Q

where are long-lived memory plasma cells

A

exist in bone marrow, mucosa, lymph nodes which drain previously infected tissue, and other locations

68
Q

when does a secondary immune response occur

A

after a reinfection with the same pathogen

69
Q

are memory T cells activated easier than naive T cells

A

yes
- they are present in the site of past infection, so are more likely to ‘see’ the pathogen first

70
Q

how long does an activated memory cell take to produce a rapid immune response

A

activated memory cells clonally expand and produce a rapid immune response in 2 - 3 days

71
Q

what is a vaccination

A

a method to produce immunity in healthy individuals

72
Q

what is a vaccination made of

A

either killed pathogen, attenuated pathogen or pieces of a pathogen that includes a primary immune response
- this primary immune response results in memory B and T cells

73
Q

what does a vaccination do

A

protect you if/when you are infected with the actual live pathogen
- the rapid secondary response destroys the pathogen in days and we are protected from the disease

74
Q

what do vaccines need

A

adjuvants

75
Q

what is an adjuvant

A

the part of the vaccine that triggers the innate immune response

76
Q

what does the innate immune response need to produce to activate the T and B cells

A

signals 2 and 3

77
Q

what happens if signals 2 and 3 are not activated in vaccines

A
  • your T and B cells with ignore the pathogen and learn to switch off their detection for the pathogen
  • this is called tolerance
  • your adaptive immune system will purposely delete T and B cells that activate without signals 2 and 3 (to avoid auto-immunity)

Immunology Midterm 1 (6 decks)

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