12- Human Microbiology

Question 1

Overview: Normal human microbiome

Answer 1

• microorganisms usually associated with human body tissue
• colonization begins at birth
• microbiomes changes over time: depending on the condition the host is subject to
  Most organism are commensal, few beneficial, even less parasitic

Question 2

Epidermis

Answer 2

Skin
Composed of:
-dead outerlayer
-living actively replicating innerlayer

Question 3

Sebatious and Apocrine sweat glands

Answer 3

Secretes: 
- Salt water
- Various amounts of proteins 
- Lipids
- Sugars 
Secretions has an antimicrobial effect thanks to lipids and proteins

Question 4

Dead cell outer skin layer

Answer 4

Creates a tough outer barrier to prevent penetration of microorganism
Generally dry and acidic: does not support the growth of microorganisms

Question 5

Skin ducts

Answer 5

Secretious ducts cary a small colony of well adapted gram-possitive bacteria:

Question 6

Skin duct microbiome

Answer 6

Secretes : bacteriocin, and aerotolerant propionobacterium acnes 
Inhabitants : 
- Yeast
-Molds 
-Bacteria

Question 7

Bacteriocon

Answer 7

kills incoming microorganic competitors, and protects against harmful bacterial colonization

Question 8

Oral cavity microbiome

Answer 8

heterogeneous microbial habitat : both aerobic and anaerobic niches
High nutrient concentration promotes growth

Question 9

Teeth: structure

Answer 9

Outer miniral matrices : Enamel

Enamel surrounds living tissue: dentin and pulp

Question 10

Dental placke formation

Answer 10

bacteria attaches to acidic glycoproteins deposited from saliva
extensive growth of microbes (streptococci) -> thick bacterial layer : plaque

Question 11

Streptococcus mutants

Answer 11

synthesizes extracellular polysaccharides : Dextran
ferments lactose (along with lactobacteria) -> produces lactic acid

Question 12

Dextrain

Answer 12

synthesized by streptococcus mutant
extra cellular polysaccharide
aids in bacterial attachement to tooth surface

Question 13

Lactic acid: plaque formation

Answer 13

lactic acid produced by Streptococcus mutants and lactobacteria degrades tooth enamel
Solubilizes calcium

Question 14

Stomach : major processes

Answer 14

secretion of acid: HCl
digestion of macromolecules
pH: 2

Question 15

Small intestine : major processes

Answer 15

continued digestion & absorption of :
- monosaccharides
- amino acids 
- fatty acids
- water 
pH: 4-5

Question 16

Large intestine : major processes

Answer 16

absorption of bile acids, vit B12

pH: 7

Question 17

Gastrointestinal [GI] tract of humans

Answer 17

colonization begins at birth
mibiomes differ in different areas of the GI determined by :
- diet
- physical environment

Question 18

Colonizing the GI tract

Answer 18

Prevented by the acidity in the stomach, dueodenum, and S intestine
Organism in food may be protected

Question 19

Microorganisms in the colon

Answer 19

mostly strict anaerobes/ facultative nanaerobes
Organisms: 
- Bacterioides 
- enteric bacteria (E. coli)
- yeasts 
- anaerobic protozoa (Entamoeba coli) 
Variability between individuals

Question 20

Microorganism in the colon: function

Answer 20

Digest :
- complex carbohydrates (cellulose, starch)
Produce: VFA’s (volatile fatty acids)

Question 21

Microorganism in the large intestine : function

Answer 21

Ferment : volatile fatty acids
Produce gasses : CO2 & H2
Methanogens : convert CO2 and H2 -.> CH4
Sulfate reducers & cysteine/methionine fermenters: produce H2S

Question 22

Nutrients produced by intestinal microorganisms

Answer 22

• amino acids

- vitamins: B12, K, thiamine, riboflavin

Question 23

Applications of GI tract microbiome

Answer 23

Microorganisms contribute to the maturing of the Gi tracts
Microbiome affect: 
- early development 
- health
- predisposition to disease (obesity)

Question 24

Microbiomae of the nose and nasopharynx

Answer 24

• staphylococci
• streptococci
• corynebacteria

Question 25

Pathogens in the nasopharynx

Answer 25

The nasopharynx may contain pathogens under control by the immune system: - Streptococci pneumoniae - Haemophilus influenza - neisseria meningitidis

Question 26

Upper respiratory tract

Answer 26

- Sinuses - Nasopharynx - Pharynx - Oral cavity - Larynx

Question 27

Lower respiratory tract

Answer 27

- Trachea - Bronci - Lungs Until recent studies LRT was considered microbiomeless : low biomass

Question 28

Genitourinary tracts

Answer 28

Men & women : generally free of microorganisms | Regular urine flushing

Question 29

Urethra pathogens

Answer 29

Possibly from GI tract: may cause disease | altered condition cause colonization-> disease

Question 30

Vaginal tract microbiome

Answer 30

Variety of microbiomes depending on age

Question 31

the vaginal tracts and glycogen

Answer 31

Glycogen concentrations controlled by hormones Glycogen is degreaded by microorganisms -> lactic acid Vaginal pH: 4.5

Question 32

Sterile zones of the human body :

Answer 32

- blood - spinal fluid - internal urinary tract (bladder, kidneys) - Peritoneal cavity (gut cavity) - Pleural cavity (lung cavity) - Sinuses - Interior regions of other body tissue (bones, muscles...)