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MBIO 3010 > Section 7 > Flashcards

Section 7 Flashcards

1
Q

What produces symptoms of infections?

A
  • Microorganisms

- Host’s immune responses

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2
Q

Define immunopathology

A

Tissue damage resulting from adaptive immune responses

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3
Q

What are the 3 types of damage that a pathogen can cause to a host?

A

1) Direct
2) Indirect via natural immune mechanisms
3) Indirect via adaptive immune mechanisms

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4
Q

What is an example of direct damage to a host by a pathogen?

A

Eating contaminated meat

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5
Q

Exotoxins are common in _____ infections

A

Bacterial

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6
Q

What are exotoxins?

A

Secreted proteins

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7
Q

Where can exotoxins be encoded?

A

On plasmids/phages

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8
Q

What is significant about a protein on a plasmid?

A

Can be passed on to different species

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9
Q

What does formaldehyde do?

A

Chemically inactivates toxins

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10
Q

What must a vaccine retain in order to work?

A

Immunogenicity

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11
Q

What do haemolysins do?

A

Cause lysis in RBC’s and many other cells

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12
Q

What is an example of a microorganism that produces pores?

A

Staph. aureus

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13
Q

Which microorganism causes scarlet fever?

A

Streptococcal erythrotoxin

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14
Q

Does heating food kill all of the bacteria and toxins?

A

Bacteria - yes

Toxins - may not be enough to denature all of them

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15
Q

What is an example of an enzyme that can destruct cell membranes and what microorganism produces it?

A

Phospholipase C produced by clostridium perfringes

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16
Q

How do staph. aureus’ pores work?

A

Similar to MAC complex

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17
Q

What is the difference between A and B subunits?

A

A is the active subunit that goes into the cell and has a toxic effect
B is the binding subunit that finds the target cells and attaches to them

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18
Q

What is the function of diphtheria toxin?

A

Block protein synthesis

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19
Q

How many subunits does the cholera toxin have?

A

5 B subunits and 1 A subunit

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20
Q

What are 2 toxins that interfere with nerve-muscle transmission?

A

Tetanus and botulinum

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21
Q

What happens to the subunits of tetanus?

A
  • A is internalized and carried to CNS

- B binds to nerve cell receptor

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22
Q

What does tetanus toxin do?

A

Blocks synaptic transmission and neurotransmitter release

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23
Q

What is the ultimate consequence of tetanus toxin?

A

Continuous stimulation of motor neurons, causing spastic paralysis

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24
Q

How is botulinum contracted?

A

Via intestine

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25
Q

What is the ultimate consequence of botulinum toxin?

A

Blocks acetylcholine release, causing flaccid paralysis

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26
Q

The pathology of tetanus and botulinum are ______

A

Opposites

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27
Q

What is the most common consequence of exotoxins?

A

Diarrhea

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28
Q

What does diarrhea allow for?

A
  • Host to rapidly get rid of infecting organism

- Parasite to spread to fresh hosts

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29
Q

What can diarrhea cause?

A

Fluid loss

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30
Q

What is the immune system very controlled with respect to?

A

Distinguishing self vs. foreign

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31
Q

What is the immune system not very controlled with respect to?

A

Degree of immune response and over-activation

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32
Q

What is the main difference between exotoxins and endotoxins?

A

Endotoxins cause systemic infections, and exotoxins have local affects

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33
Q

What is the main function of endotoxins?

A

Activate immune system and induce cytokines

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34
Q

When are endotoxins released?

A

When cells die

35
Q

What type of organisms are endotoxins attached to?

A

Gram negative!!

36
Q

Where are endotoxins typically found?

A

In LPS

37
Q

What do endotoxins consist of?

A

Lipid A, core oligosaccharide, and O-polysaccharide

38
Q

What is the function of lipid A in an endotoxin?

A

Responsible for much of the toxic activity

39
Q

What is the function of O-polysaccharide in an endotoxin?

A

Responsible for serologic diversity

40
Q

What do endotoxins cause?

A

Fever and shock, as well as liver toxicity, hypoglycemia, and clumping of platelets

41
Q

How is a fever caused?

A

Release of cytokines by macrophages in response to LPS

42
Q

What does shock lead to?

A

Decreased blood pressure, which leads to a lack of oxygen to organs, causing organ failure

43
Q

Why is a bloodstream infection of a gram negative organism VERY serious?

A

Because it will release endotoxins, which can cause organ failure

44
Q

What does TSST-1 do?

A

Causes T-cells to release cytokines

45
Q

What type of cells can endotoxins act on?

A

Endothelial cells

46
Q

What is the treatment for gram negative organisms?

A

Very heavy dose of antibiotics

47
Q

What can LPS activate and which part activates it?

A

Alternative (polysaccharide) and classical (lipid A) complement pathways

48
Q

What does activation of the complement pathways cause?

A

Cells become sticky, which will cause a decrease in oxygen (if this occurs in airways) leading to organ failure

49
Q

Which allergic responses are antibody-mediated?

A

1, 2, and 3

50
Q

Which allergic response is cell-mediated?

A

4

51
Q

Define hypersensitivity

A

Overreaction of the immune system

52
Q

Which is the most common allergic response?

A

1

53
Q

Type 1 allergic response is a reaction to ______

A

An allergen in the environment

54
Q

What is the function of effector cells?

A

Respond to presence of allergen in the body

55
Q

Are symptoms always related to actual point of entrance of the allergen?

A

No, not always

56
Q

What type of genetic disorder can cause allergies?

A

Overproduction of IL-4

57
Q

What does overproduction of IL-4 lead to?

A

Selection of IgE production over IgG and increased IL-4 receptors on B cells

58
Q

What are the steps that occur after an initial exposure to an allergen?

A
  • IgE formation
  • IgE binds via Fc portion to specific receptors on basophils in blood and mast cells in tissues
  • Histamine release
59
Q

Do signs appear after the first interaction with an allergen?

A

Not necessarily

60
Q

What are the steps that occur after the second or subsequent exposure to an allergen?

A
  • Allergen binds to V region of the Fab
  • Crosslinks 2 adjacent IgE molecules on mast cell/basophil surface
  • Triggers degranulation and release of histamine
  • Immediate response
61
Q

What are symptoms of a type 1 allergic response?

A
  • Hay fever
  • Swelling and itchiness
  • Anaphylaxis
62
Q

What can anaphylaxis lead to?

A

Bronchoconstriction => asphyxiation => shock

63
Q

What are the key mediators of type 1 allergic responses?

A

Histamine and SRS-A

64
Q

What does histamine cause?

A

Vasodilation, increased capillary permeability, and smooth muscle contraction

65
Q

What do antihistamines do?

A

Block binding of histamine molecules to receptors, resulting in no allergy symptoms

66
Q

What does SRS-A stand for?

A

Slow reacting substance of anaphylaxis

67
Q

What is the main difference between histamine and SRS-A?

A

Histamine is pre-formed and present within granules, which SRS-A is produced after exposure to allergen

68
Q

What is the function of SRS-A?

A

Bronchoconstrictor implicated in asthma

69
Q

How are chronic allergies treated?

A

Antihistamines and corticosteroids

70
Q

What do corticosteroids do?

A

Block degranulation of mast cells

71
Q

How are acute allergies treated?

A

Epinephrine, followed by IV antihistamines

72
Q

What does epinephrine do?

A
  • Increases cAMP levels which decreased mediator release

- Increased blood pressure to prevent shock

73
Q

What occurs in type 2 cytotoxic hypersensitivity reactions?

A

IgG is produced and binds to non-self cell surface and activates classical complement pathway, producing MAC complex

74
Q

What are examples of type 2 cytotoxic hypersensitivity reactions?

A

ABO blood transfusions and Rh incompatibility

75
Q

What occurs in type 3 immune complex hypersensitivity reactions?

A
  • Large Ab-Ag complexes precipitate and induce inflammation

- Activation of complement, attraction of phagocytes, and general tissue damage

76
Q

What is damaged in type 3 immune complex hypersensitivity reactions?

A

Lungs, kidneys, and joints

77
Q

Which cells mediate type 4 reactions?

A

Th and Tc cells

78
Q

What can type 4 hypersensitivity reactions cause?

A

Some tissue destruction

79
Q

When do type 4 hypersensitivity reactions start?

A

Hours/days after contact

80
Q

How long to type 4 hypersensitivity reactions last?

A

Days

81
Q

H. pylori is associated with _______ cancer

A

Stomach

82
Q

What is the most important virulence factor of H. pylori?

A

Urease enzyme

83
Q

Can H. pylori be treated with antibiotics?

A

Yes

MBIO 3010 (17 decks)

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