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Microbiology > Lecture 12 > Flashcards

Lecture 12 Flashcards

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Biology 101 flashcards
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

A

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

23
Q

disruptions of skin microbiome

A

acne (pore blockage), body odor, and disease

24
Q

oral cavity microbiome

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
Q

oral cavity characteristics

A

heterogeneous habitat
antimicrobial chemicals present (saliva contains lysozyme)
The nutrient source is food particles and cell debris near gums/teeth

26
Q

Dental plaques and tooth decay

A

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
Q

formation of dental caries

A

tooth surface is easy to clean but gingival crevice is not

28
Q

preventing dental caries

A

restrict sucrose intake
brush your teeth
enhance enamel with fluoride

29
Q

GI tract microbiome

A

very large surface area (400 m^2) and high microbial diversity (1000 species)

30
Q

GI tract characteristics

A

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
Q

stomach microbiome

A

highly acidic fluids (pH=2)
only acidophiles can survive
- low diversity

32
Q

small intestine microbiome

A

fairly acidic (pH= 4-5)
similar microbiome to the stomach
competition with the microbiome since we absorb our nutrients here

33
Q

large intestine

A

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
Q

functions of intestinal microbes

A

vitamin synthesis (B12 and K) and steriod metabolism (microbes convert)
gas production

35
Q

Microbiome turnover

A

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
Q

Disrupting the resident intestinal microbiome

A

diarrhea, alteration of digestive function, and pathogen colonization

37
Q

Restoring the resident intestinal microbiome

A

probiotics and fecal microbiota transplant

38
Q

mucosal tissue microbiome

A

large surface area (100m^2) and low microbial diversity (60 species)

39
Q

mucosal tissue characteristics

A

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
Q

Virulence

A

a measure of pathogenicity
(how much harm it causes measured on a scale)

41
Q

Pathogenesis

A

process by which microbes cause disease
adherence, invasion, and infection

42
Q

Measuring virulence

A

LD50 (amount of pathogen that kills 50% of host individuals)
low v high LD50

43
Q

Attenuation

A

decrease/loss of virulence
often used as vaccines
in nature there is a selection for attenuation

44
Q

Adherence

A

attachment to host cells
highly specific to certain cell types
mechanisms: slime layers and capsules & pili

45
Q

Invasion

A

entering host tissues and causing damage/disease
most invasion occurs through wounds

46
Q

infection

A

growth/production of toxins and virulence factors

47
Q

Virulence factors

A

promote colonization and growth of pathogens
ex. toxins, capsules, and pili

48
Q

toxins

A

chemicals that inhibit cell function or kill cells

49
Q

Exotoxins

A

released from pathogen cells
types: cytolytic (damage to cytoplasmic membrane) and AB ( inhibit internal cell functions)

50
Q

alpha-toxin

A

cytolytic toxin
pore in membrane that allows for influx and efflux of various components (causes cell to lyse)
done by staphylococcus spp.

51
Q

diptheria

A

AB toxin
binds to receptor protein that stop protein synthesis
done by cornebacterium

52
Q

endotoxins

A

not released from pathogen cells
present in LPS of outer membrane
less toxic than exotoxins
ex. salmonella endotoxins

53
Q

Barriers to infection

A

physical (skin), chemical (antimicrobial and low/changing pH), and biological (competition w/ resident microbiome)

54
Q

Risk factors

A

increase infection susceptibility
risk factors examples:
age, diet, and stress

Microbiology (19 decks)

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