Chapter 24 - Human Microbiota

Question 1

symbiosis

Answer 1

various living arrangements between different species of organisms in their environment
- can be harmful, beneficial, or neutral

Question 2

commensalism

Answer 2

neither is harmed or benefitted

Question 3

mutaulism

Answer 3

both organisms benefit (often obligatory)

Question 4

parasitism

Answer 4

one species benefits while the other is harmed

Question 5

pathogens

Answer 5

subset of parasites that cause disease

Question 6

microbiome

Answer 6

functional collection of microbes in a particular environmental system

Question 7

microbiota

Answer 7

all microbes within a microhabitat (ie. skin microbiota)

Question 8

How many microbes on the human micrombiome?

Answer 8

10^13

Question 9

Stomach Microbiota

Answer 9

Firmicutes, Bacteroidetes, Actinobacteria
- H. pylori (acidophile) - pathogenic, chronic inflammation

Question 10

Large Intestine Microbiota

Answer 10

Colon = in vivo fermentations vessel
- most bacteria restricted in the lumen
- facultative aerobes
Bacteroidetes and gram-positive bacteria
(some methanogenic archaea)

Question 11

Gut Microbiota

Answer 11

Firmicutes, Bacteroidetes, Proteobacteria
- limit phylum level diversity, but much species diversity

Question 12

Gut Enterotypes

Answer 12

1. Bacteroides
2. Prevotella
3. Ruminococcus

Question 13

Mucous Membrane

Answer 13

Support microbiota growth
- prevent infection of pathogens
- secrete mucin

Question 14

Mucin

Answer 14

secreted by mucous membrane
- retains moisture, inhibit microbial attachment

Question 15

Saliva

Answer 15

contains antimicrobial enzymes (lysozymes)

Question 16

Mouth microbial

Answer 16

lots of nutrients near the surface of the mouth promote localized microbial growth
- change w age (aerotolerant anaerobes -> anaerobes)
plaque (biofilm) wear down tooth enamel by fermentation

Question 17

Respiratory Microbiota

Answer 17

enter through breathing
- most trapped in nasal cavity and swallowed to be killed in stomach
lower respiratory tract has no microbiota in healthy adults

Question 18

Resident microbiota

Answer 18

microbes that constantly live in/on our bodies

Question 19

Transient microbiota

Answer 19

microbes that are temporarily found in/on our bodies

Question 20

Skin Microbiota

Answer 20

great diversity of microbes, dependent on location (chemical composition/moisture)
- lots of transient microbes

Question 21

Human Microbiome Project (HMP)

Answer 21

Studied hundreds of medical students over many years to make a baseline for healthy human microbiome
- Flawed - didn’t account for diet, culture, or lifestyle attributions

Question 22

IBD

Answer 22

Inflammatory Bowel Disease
- an imbalance of immune system and normal gut microbiota
- antibiotic use increases risk
- may be transmissible to family members
- american diet may be linked (high in animal protein and carbs)

Question 23

obesity

Answer 23

• colonization linked to glucose uptake and lipid absorption
• more methanogens: increase fermentation: increased long chain fatty acids: obesity

Question 24

Antibiotics in Humans

Answer 24

kill all microbes (non-specific)
- use within first few months may increase risk of IBD/other disorders realted to dysbiosis

Question 25

Fecal Transplant

Answer 25

Clostridium difficile: resistant to antibiotic use, fecal transplants used to treat infections

Question 26

Probiotics

Answer 26

live organisms that benefit the human microbiome (Bifidobacterium and Lactobacillus)

Question 27

Prebiotics

Answer 27

typically carbs that are indigestible for humans but can be fermented by microbes