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Microbes and You > Microorganisms and Human gut L2 > Flashcards

Microorganisms and Human gut L2 Flashcards

1
Q

what is the importance of the mucosal surface of the gut

A

largest body surface in contact with outside world

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2
Q

what is the gastrointestinal tract made of

A

epithelial cells

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3
Q

why are gastrointestinal cells made of epithelial cells

A

for digestion of food and absorption of nutrient

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4
Q

what does the mucosal immune system create

A

creates tolerance to harmless dietary and commensal flora antigens

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5
Q

what does the mucosal immune system prevent

A

pathogens crossing epithelium = mucosal barrier

uptake of foreign antigens

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6
Q

what is the newborn gastrointestinal system like

A

gut microbiome GI tract of newborn is sterile

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7
Q

when do newborns gut microbiome become colonised

A

First colonising organisms occur during birth – flora will vary depending on birth method
Flora rapidly acquired from a variety of sources e.g. food

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8
Q

what is the oral microbiome

A

Complex flora >400 species of bacteria colonise the gums, tongue, cheek surfaces, teeth and other parts of oral cavity

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9
Q

how does the oral microbiome change

A

Changes with age as a child gains teeth

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10
Q

how do plaques change

A

Plaque can form within 24 hours of cleaning

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11
Q

what is the stomach and duodenum main function

A

retention and digestion of food and liquid

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12
Q

what is the stomach and duodenum organisms like

A

mainly transient

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13
Q

what is the stomach and duodenum tolerant to

A

low pH

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14
Q

what shape is helicobacter pylori

A

Helical shaped bacterium

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15
Q

what respiration type is helicobacter pylori

A

Microaerophile – can grow in low oxygen environments

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16
Q

how does helicobacter pylori produce energy

A

Produces its energy by using hydrogenases to oxidise H2 produced by intestinal bacteria

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17
Q

what does helicobacter pylori do to urea

A

Converts urea to NH2 and CO2 using ureases

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18
Q

what does NH2 do to host cells

A

NH2 plus other products (such as proteases)

damage host cells

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19
Q

what effect does NH2 have when damage host cells

A

causes stomach ulcers – can result in stomach cancer in some people

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20
Q

what is the small intestine made of

A

jejunum and ileum

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21
Q

how does the small intestine kill bacteria

A

Natural peristaltic action of gut keeps bacterial numbers low – high rate of transfer of contents to the large intestine

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22
Q

what is the main function of the small intestine

A

absorption of digested food

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23
Q

what is the pH of small intestine

A

neutral pH

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24
Q

what is the colons main function

A

absorption of liquids and compaction of undigested food into faeces

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25
Q

where are the most bacterial cells

A

colon contains the greatest number of bacterial cells and most different species

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26
Q

what are most of the colon microbiota respiration

A

Majority are strict anaerobes – can’t survive in presence of oxygen

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27
Q

where is bifidobacterium

A

Natural part of the gut flora

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28
Q

what bacteria are early gut colonisers

A

bifidobacterium

especially in breast fed infants

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29
Q

what do bifidobacterium act as

A

immunomodulators

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30
Q

what does bifidobacterium do

A

absorb procarcinogens, promote attack on malignant cells

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31
Q

effect of bifidobacterium on cholesterol and triglycerides

A

Lowers blood cholesterol and triglycerides

32
Q

what effect does bifidobacterium have on food intolerances

A

Reduce food intolerances foodborne allergies

33
Q

what effect does bifidobacterium have on intestinal flora

A

restores normal intestinal flora

34
Q

what does bifidobacterium produce

A

nutrients

35
Q

what does bifidobacterium reduce

A

liver toxins

36
Q

what does bifidobacterium improve

A

mineral absorption

37
Q

what growth does bifidobacterium inhibit

A

Inhibit growth of harmful bacteria and yeasts

38
Q

what is the gut archaea like

A

Gut archaea more limited than bacterial and eukaryotic microorganisms

39
Q

what is the archaea colonisation like

A

Variable colonisation – only about 50% of humans have detectable archael populations in the gut

40
Q

what are the dominant archaea in the gut

A

methanogens

41
Q

what do methanogens make

A

methane

42
Q

what would happen if the gut flora was removed

A

Without gut flora, human body wouldn’t be able to utilise some undigested carbohydrates it consumes

43
Q

what can some plant cells do that human cells cannot

A

Some species can break down polysaccharides (such as cellulose, from plant cells) which human cells cannot produce the enzymes for digestion

44
Q

what do bacteria do to carbohydrates

A

Carbohydrates turned into short chain fatty acids by bacteria

45
Q

what can bacteria make

A

small amounts of vitamins e.g. vitamins K and B7 (biotin)

46
Q

what are SCFA

A

short chain fatty acids

47
Q

where are SCFA made

A

bacteria in colon

48
Q

what is the effect of SCFA

A

increase cell proliferation throughout whole gut

49
Q

what do SCFA promote

A

water absorption - prevent osmotic diarrhoea

50
Q

what growth do SCFA help inhibit

A

Help inhibit pathogenic bacteria growth

51
Q

what is acetic acid

A

energy source, used as a substrate for fat synthesis in the liver

52
Q

what is propionic acid

A

energy source for liver, may reduce synthesis of cholesterol

53
Q

what is butyric acid

A

major energy source for colon cells, can stimulate the differentiation and programmed cell death of cancer cells

54
Q

what can some gut bacteria make

A
  • Carcinogens and toxins
  • Phenols and paracresols
  • H2S, hydrogen sulphide
  • Secondary bile acids, may cause cancer
55
Q

what are the protein products catabolism

A

phenols and paracresols

56
Q

what can protein products catabolism cause

A

may injure mucosa and influence the brain

57
Q

what is toxic to the colon cells

A

hydrogen sulphide

58
Q

what can cause the gut microflora composition to vary

A
  • age
  • nature of foods eaten
  • individual
59
Q

what is SIBO

A

Small Intestine Bacterial Overgrowth

60
Q

what can happen if the gut microbiota is altered

A

Can cause various illnesses, one of which is SIBO

61
Q

what does the bacterial composition of the ileum resemble

A

Bacterial composition of ileum resembles that found in the colon

62
Q

what stimulates the growth of bacteria in the ileum

A

Ileum has greater nutrient content – stimulates growth of bacteria

63
Q

what can cause the gut microbiota to be altered

A

May be caused by backwards invasion from colon

64
Q

what does the gut microbiota alteration tend to be caused by

A

Tends to be caused by anything that inhibits natural movement of gut and the transit of food and gut contents through the GI tract

65
Q

what can SIBO result in the undesirable by-products of the use of greater nutrients

A
  • gas production
  • bloating (due to excess gas)
  • diarrhoea / constipation
  • abdominal pain
66
Q

what are the symptoms of SIBO

A

Vitamin and mineral deficiencies as well as weight loss as the absorptive function of the small intestine may be reduced

67
Q

what does Clostridium difficile cause

A

pseudomembranous colitis and antibiotic-associated diarrhoea

68
Q

what effect does pseudomembranous colitis and antibiotic-associated diarrhoea have

A

Alters normal intestinal flora, often causes problems after use of broad spectrum antibiotics
takes over the gut whilst missing usual flora

69
Q

what is the treatment for clostridium difficile

A

Stool transplant, over 90% of patients that receive a stool transplant recover
A stool transplant – Faecal microbiota transplantation (FMT)

70
Q

what does FMT do

A

restores natural colonic flora by introducing healthy bacterial flora (from a healthy donor) through infusion of stool by e.g. an enema

71
Q

what does clostridium difficile produce

A

toxin A and toxin B

72
Q

where is clostridium difficile common

A

Common amongst hospitalised patients, elderly and those with underlying diseases

73
Q

what are the effects of mild cases of clostridium difficile

A

frequent foul-smelling and watery stools

74
Q

what are the effects of severe cases of clostridium difficile

A

pseudomembranous colitis, results in diarrhoea containing blood mucus, severe abdominal cramps

75
Q

how can clostridium difficile effect the heart

A

May result in an abnormal heart rhythm or heart attack due to altered electrolyte levels in blood

Microbes and You (14 decks)

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