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MBIO 3010 > Section 4 > Flashcards

Section 4 Flashcards

1
Q

What are some ways that a pathogen can gain entry through external host surfaces?

A
  • Skin

- Mucosal lining

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2
Q

What do pathogens need for attachment to a host?

A

Receptor

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3
Q

What receptors does HIV need?

A

CD4 and CCR5

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4
Q

What receptor does EBV need?

A

C3d

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5
Q

Why is the exit strategy of a pathogen very important?

A

In order for the pathogen to survive it needs to leave an infected host and spread to a healthy host

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6
Q

What are some ways that a pathogen can exit a host?

A
  • Body fluid

- Vectors (insects)

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7
Q

What does the skin use as protection against microorganisms?

A
  • Fatty acids
  • Sebaceous gland secretions
  • Compounds secreted by normal flora
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8
Q

Dead skin cells are part of the ____ immune system

A

Innate

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9
Q

How do dead skin cells protect against infection?

A

By adding to the barrier (if an organism attaches to dead skin, it will just fall off later)

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10
Q

Do dead skin cells aid in the replication of a virus?

A

No because a virus needs a live cell

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11
Q

What mechanisms does the conjunctiva use to protect against pathogens?

A
  • Eyelashes

- Tears

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12
Q

What chemicals are found in tears that aid in protection?

A
  • Lysozyme
  • IgA
  • Lactoferrin
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13
Q

What are often the source of conjunctiva infections?

A

Contaminated fingers/towels

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14
Q

How does the respiratory tract avoid infection?

A

Inhaled microorganisms that become entrapped in mucous are carried up to the throat via ciliary escalator and swallowed

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15
Q

How can organisms avoid cleansing by the respiratory tract?

A
  • Attach via adhesins to specific cell-surface receptors on epithelial cells
  • Inhibit ciliary action
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16
Q

What is an example of a pathogen that inhibits ciliary action?

A

Whooping cough

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17
Q

What are ways that a microorganism can cause infection in the respiratory tract?

A
  • Avoid cleansing

- Avoid destruction by alveolar macrophages

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18
Q

What can be deduced when a respiratory tract infection goes away within a week?

A

It is a viral infection

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19
Q

What can be deduced when a respiratory tract infection doesn’t go away by itself and secretions become thick, green mucous?

A

It is a secondary bacterial infection

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20
Q

What are the defences of the oropharynx?

A
  • Flushing action of saliva
  • Chewing and actions of tongue, lips, and cheeks
  • Secretory IgA
  • Lysozyme
  • Leukocytes in saliva and at mucosal surfaces
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21
Q

What does being dehydrated lead to?

A

Decreased saliva, which means bacteria grows faster, which causes bad breath

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22
Q

What do microbes need to attach to in the oropharynx?

A

Mucosa and/or tooth surfaces

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23
Q

What is peristalsis?

A

The physical movement of cells that prevents attachment of microorganisms

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24
Q

How does mucous act as a barrier in the GI tract?

A

Mucous covers the attachment site for a pathogen

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25
_____ are highly resistant to acid
Spore formers
26
The urogenital tract is a ______ tract
Continuous
27
Does the vagina have a cleansing mechanism?
No
28
When does lactobacilli colonization occur?
Reproductive years
29
How do lactobacilli act as a defence for the urogenital tract?
Lactobacilli use glycogen as a carbon source, and from glycogen they synthesize lactic acid which decreases the pH of urogenital tract, making it very hard for pathogens to survive
30
What is an easy way to test if a woman has a yeast infection?
Test pH -- if pH is around 6 then the woman has a yeast infection
31
What can cause impaired defences of the urogenital tract?
Estrogen imbalance
32
What are the defences of the bladder and urethra?
- Flushing action of urine | - Mucosal layer of bladder that has IgA
33
How can organisms avoid IgA?
By inactivating it with proteases
34
How can a microorganism invade the urogenital tract via the urethra?
By avoiding the flushing action of urine
35
Organisms that are good at infecting the urogenital tract usually have ____
Pilli
36
Are circumcised males more or less prone to urogenital infections?
Less
37
How do pathogens exit the body?
- Shed from body surfaces | - Extracted via insects
38
What are the factors that affect transmission?
- Numbers shed - Stability in environment - Efficiency of infection
39
Will an organism that can produce coughing and sneezing be more or less successful than an organism that produces tears?
More
40
What does a pathogen have to have to be stable in the external environment?
Resistance to desiccation and thermal inactivation
41
How can fecal-oral transmission be controlled?
By providing everyone with clean water and food
42
How can venereal transmission be controlled?
By asking people to change their behaviour, which makes it harder to control
43
What does transmission by vector mean?
Plague, flea
44
How are pathogens transmitted via the respiratory tract?
- Nasal secretions - Sneezing - Other sources such as tissues, hands, other surfaces
45
What size of droplets tend to settle?
4m
46
What size of droplets get trapped in nasal mucosa?
10 uM
47
What size of droplets get suspended in air indefinitely?
1-4 uM
48
Are viruses or bacteria transmitted via the respiratory tract and why?
- Viruses | - Bacteria clump together and will be bigger than the normal size of a droplet so people are less likely to get infected
49
What are methods of transmission from the GI tract?
- Fecal-oral | - Contaminated drinking water
50
How are GI diseases spread in resource-rich countries?
Food and fingers
51
How are GI diseases spread in resource-poor countries?
Water and fleas
52
How are STI's transmitted?
- Discharge | - Mucosal sores
53
What pathogens are transmitted via mucosal sores?
Herpes and HPV
54
What pathogens are transmitted via semen?
Cytomegalovirus, HBV, and HIV
55
What are methods of transmission from urogenital tract?
- STI - Semen - Perinatal
56
What pathogens are transmitted via saliva?
Paramyxovirus, HSV, and cytomegalovirus
57
What is the most common transmission through the skin?
Direct contact
58
What pathogens are transmitted via needles and transfusion?
Hepatitis B, hepatitis C, and HIV
59
What is vertical transmission?
When a microorganism is transmitted from one generation to another
60
Is vertical transmission or horizontal transmission faster?
Horizontal
61
Does vertical or horizontal transmission affect a larger population?
Horizontal
62
What is horizontal transmission?
When a microorganism is transmitted through one generation
63
How is transmission from animals acquired in urban areas?
- Eating/drinking infected animal products - Contact with domestic pets - Occupational
64
What can be contracted from reptiles?
Salmonella in their droppings
65
What can be contracted from dogs?
Toxocariasis
66
What can be contracted from cats?
Toxoplasmosis
67
What are examples of occupational factors that can cause transmission from animals?
- Butchers touching raw meat | - Farmers with livestock
68
What is an example of a motile bacteria that can propel through mucous?
E. coli

MBIO 3010 (17 decks)

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