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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
What is the ultimate consequence of botulinum toxin?
Blocks acetylcholine release, causing flaccid paralysis
26
The pathology of tetanus and botulinum are ______
Opposites
27
What is the most common consequence of exotoxins?
Diarrhea
28
What does diarrhea allow for?
- Host to rapidly get rid of infecting organism | - Parasite to spread to fresh hosts
29
What can diarrhea cause?
Fluid loss
30
What is the immune system very controlled with respect to?
Distinguishing self vs. foreign
31
What is the immune system not very controlled with respect to?
Degree of immune response and over-activation
32
What is the main difference between exotoxins and endotoxins?
Endotoxins cause systemic infections, and exotoxins have local affects
33
What is the main function of endotoxins?
Activate immune system and induce cytokines
34
When are endotoxins released?
When cells die
35
What type of organisms are endotoxins attached to?
Gram negative!!
36
Where are endotoxins typically found?
In LPS
37
What do endotoxins consist of?
Lipid A, core oligosaccharide, and O-polysaccharide
38
What is the function of lipid A in an endotoxin?
Responsible for much of the toxic activity
39
What is the function of O-polysaccharide in an endotoxin?
Responsible for serologic diversity
40
What do endotoxins cause?
Fever and shock, as well as liver toxicity, hypoglycemia, and clumping of platelets
41
How is a fever caused?
Release of cytokines by macrophages in response to LPS
42
What does shock lead to?
Decreased blood pressure, which leads to a lack of oxygen to organs, causing organ failure
43
Why is a bloodstream infection of a gram negative organism VERY serious?
Because it will release endotoxins, which can cause organ failure
44
What does TSST-1 do?
Causes T-cells to release cytokines
45
What type of cells can endotoxins act on?
Endothelial cells
46
What is the treatment for gram negative organisms?
Very heavy dose of antibiotics
47
What can LPS activate and which part activates it?
Alternative (polysaccharide) and classical (lipid A) complement pathways
48
What does activation of the complement pathways cause?
Cells become sticky, which will cause a decrease in oxygen (if this occurs in airways) leading to organ failure
49
Which allergic responses are antibody-mediated?
1, 2, and 3
50
Which allergic response is cell-mediated?
4
51
Define hypersensitivity
Overreaction of the immune system
52
Which is the most common allergic response?
1
53
Type 1 allergic response is a reaction to ______
An allergen in the environment
54
What is the function of effector cells?
Respond to presence of allergen in the body
55
Are symptoms always related to actual point of entrance of the allergen?
No, not always
56
What type of genetic disorder can cause allergies?
Overproduction of IL-4
57
What does overproduction of IL-4 lead to?
Selection of IgE production over IgG and increased IL-4 receptors on B cells
58
What are the steps that occur after an initial exposure to an allergen?
- IgE formation - IgE binds via Fc portion to specific receptors on basophils in blood and mast cells in tissues - Histamine release
59
Do signs appear after the first interaction with an allergen?
Not necessarily
60
What are the steps that occur after the second or subsequent exposure to an allergen?
- 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
What are symptoms of a type 1 allergic response?
- Hay fever - Swelling and itchiness - Anaphylaxis
62
What can anaphylaxis lead to?
Bronchoconstriction => asphyxiation => shock
63
What are the key mediators of type 1 allergic responses?
Histamine and SRS-A
64
What does histamine cause?
Vasodilation, increased capillary permeability, and smooth muscle contraction
65
What do antihistamines do?
Block binding of histamine molecules to receptors, resulting in no allergy symptoms
66
What does SRS-A stand for?
Slow reacting substance of anaphylaxis
67
What is the main difference between histamine and SRS-A?
Histamine is pre-formed and present within granules, which SRS-A is produced after exposure to allergen
68
What is the function of SRS-A?
Bronchoconstrictor implicated in asthma
69
How are chronic allergies treated?
Antihistamines and corticosteroids
70
What do corticosteroids do?
Block degranulation of mast cells
71
How are acute allergies treated?
Epinephrine, followed by IV antihistamines
72
What does epinephrine do?
- Increases cAMP levels which decreased mediator release | - Increased blood pressure to prevent shock
73
What occurs in type 2 cytotoxic hypersensitivity reactions?
IgG is produced and binds to non-self cell surface and activates classical complement pathway, producing MAC complex
74
What are examples of type 2 cytotoxic hypersensitivity reactions?
ABO blood transfusions and Rh incompatibility
75
What occurs in type 3 immune complex hypersensitivity reactions?
- Large Ab-Ag complexes precipitate and induce inflammation | - Activation of complement, attraction of phagocytes, and general tissue damage
76
What is damaged in type 3 immune complex hypersensitivity reactions?
Lungs, kidneys, and joints
77
Which cells mediate type 4 reactions?
Th and Tc cells
78
What can type 4 hypersensitivity reactions cause?
Some tissue destruction
79
When do type 4 hypersensitivity reactions start?
Hours/days after contact
80
How long to type 4 hypersensitivity reactions last?
Days
81
H. pylori is associated with _______ cancer
Stomach
82
What is the most important virulence factor of H. pylori?
Urease enzyme
83
Can H. pylori be treated with antibiotics?
Yes

MBIO 3010 (17 decks)

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