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Microbiology > Lecture 12 > Flashcards

Lecture 12 Flashcards

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1
Q

each human body hosts

A

40 trillion microbes

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2
Q

microbiota

A

= microflora
all microbial species

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3
Q

microbiome

A

all microbial species and their interactions

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4
Q

resident microbiome

A

microbes in a healthy human body

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5
Q

where do resident microbiomes occur?

A

skin, respiratory tract, digestive tract, and urogenital tract
*exposed to environment

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6
Q

where do resident microbiomes NOT occur?

A

internal organs, blood, lymph, and nervous system
*not exposed to environment

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7
Q

what affects the various resident microbiomes?

A

O2 levels, acidity (pH), and nutrient availability
different body area = different habitats (microenvironments)

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8
Q

benign effects of microbiomes

A

no positive/negative effect
occupy human microhabitats
most common

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9
Q

beneficial effects of microbiomes

A

positive effect
metabolism and defense
occurs some of the time

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10
Q

pathogenic effects of microbiomes

A

negative effect
cause infectious diseases
occurs only a few times (more rare)

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11
Q

Positive effects of the microbiome

A

immune system maintenance and development
aids in nutrition (combating obesity depending on microbiome)
aids in neurological functioning

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12
Q

how are resident microbiomes established?

A

the first exposure is from delivery (vaginal v. c-section)
human interventions for c-section babies (vaginal seeding or bacterial baptism)
continued exposure and prebiotics from breastfeeding
from the environment, thus variable

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13
Q

The uterus is a

A

sterile environment
- no pre-birth exposure to microbes
- humans are born without a microbiome

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14
Q

how are resident microbiomes maintained?

A

Clear out a large number of bacteria every day, will grow back
Zones of containment minimize bacteria-epithelial cell contact
outer (general defense) and inner (specific defense) mucous layers

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15
Q

host-pathogen interactions

A

pathogens live on/in hosts and cause disease
cause disease in the absence of normal host resistance

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16
Q

dysbiosis

A

imbalanced or impaired microbiome

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17
Q

Skin microbiome

A

medium surface area (2 m^2) and high microbial diversity (1000 species)

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18
Q

Skin microbiome characteristics

A

heterogeneous habitat
has multiple microenvironments (sebaceous, moist, and dry)
antimicrobial chemicals present (sweat)
nutrient sources (sebum– oily secretion)

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19
Q

Sebaceous skin microbiome

A

upper chest
oily areas

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20
Q

moist skin microbiome

A

armpits
high moisture

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21
Q

dry skin microbiome

A

forearms
low moisture

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22
Q

Factors affecting the skin microbiome

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A

age and personal hygiene (host factors)
weather (environmental factor)

23
Q

disruptions of skin microbiome

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A

acne (pore blockage), body odor, and disease

24
Q

oral cavity microbiome

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A

small surface area (0.2 m^2) and medium microbial diversity (600 species)
primarily anaerobic metabolism
- facultative aerobes and obligate anaerobes
– make a biofilm

25
oral cavity characteristics
heterogeneous habitat antimicrobial chemicals present (saliva contains lysozyme) The nutrient source is food particles and cell debris near gums/teeth
26
Dental plaques and tooth decay
teeth are made of enamel and the lactic acids produced by certain bacteria break down the enamel leads to dental caries aka tooth decay
27
formation of dental caries
tooth surface is easy to clean but gingival crevice is not
28
preventing dental caries
restrict sucrose intake brush your teeth enhance enamel with fluoride
29
GI tract microbiome
very large surface area (400 m^2) and high microbial diversity (1000 species)
30
GI tract characteristics
heterogeneous habitat (stomach, small & large intestines) antimicrobial conditions (low pH in stomach and antibodies in intestines) nutrient sources (a ton from a high diversity of food intake and processing)
31
stomach microbiome
highly acidic fluids (pH=2) only acidophiles can survive - low diversity
32
small intestine microbiome
fairly acidic (pH= 4-5) similar microbiome to the stomach competition with the microbiome since we absorb our nutrients here
33
large intestine
neutral (pH=7) strictly anoxic (No O2- anaerobic) mainly absorb H2O here so less competition most diversity (10 to 100 billion cells per gram) "fermentation vessel"
34
functions of intestinal microbes
vitamin synthesis (B12 and K) and steriod metabolism (microbes convert) gas production
35
Microbiome turnover
10 trillion bacteria are removed each day - fecal matter is one-third bacterial cells Remaining bacteria continue to grow - populations double 1-2x per day
36
Disrupting the resident intestinal microbiome
diarrhea, alteration of digestive function, and pathogen colonization
37
Restoring the resident intestinal microbiome
probiotics and fecal microbiota transplant
38
mucosal tissue microbiome
large surface area (100m^2) and low microbial diversity (60 species)
39
mucosal tissue characteristics
homogenous habitat (upper v lower respiratory and urogenital tract) antimicrobial conditions (ex low pH in Vagina) nutrient sources (mucus secretions) *low diversity of microbes
40
Virulence
a measure of pathogenicity (how much harm it causes measured on a scale)
41
Pathogenesis
process by which microbes cause disease adherence, invasion, and infection
42
Measuring virulence
LD50 (amount of pathogen that kills 50% of host individuals) low v high LD50
43
Attenuation
decrease/loss of virulence often used as vaccines in nature there is a selection for attenuation
44
Adherence
attachment to host cells highly specific to certain cell types mechanisms: slime layers and capsules & pili
45
Invasion
entering host tissues and causing damage/disease most invasion occurs through wounds
46
infection
growth/production of toxins and virulence factors
47
Virulence factors
promote colonization and growth of pathogens ex. toxins, capsules, and pili
48
toxins
chemicals that inhibit cell function or kill cells
49
Exotoxins
released from pathogen cells types: cytolytic (damage to cytoplasmic membrane) and AB ( inhibit internal cell functions)
50
alpha-toxin
cytolytic toxin pore in membrane that allows for influx and efflux of various components (causes cell to lyse) done by staphylococcus spp.
51
diptheria
AB toxin binds to receptor protein that stop protein synthesis done by cornebacterium
52
endotoxins
not released from pathogen cells present in LPS of outer membrane less toxic than exotoxins ex. salmonella endotoxins
53
Barriers to infection
physical (skin), chemical (antimicrobial and low/changing pH), and biological (competition w/ resident microbiome)
54
Risk factors
increase infection susceptibility risk factors examples: age, diet, and stress

Microbiology (19 decks)

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