prokaryotic microorganisms in their natural habitats - human body

Question 1

what is the human microbiome?

Answer 1

the human microbiome is the community of microorganisms (bacteria, fungi, and viruses) that exist in/on the body.

Question 2

what is the role of bacteria in the human body?

Answer 2

bacteria in the human body play a huge role in health, they help digest food, and provide immunity. they preform important function - e.g. degradation of carbohydrates, production of fatty acids, and production of amino acids and vitamins.

Question 3

what is the natural flora?

Answer 3

the natural flora is a population of microorganisms that infect the body without necessarily causing disease.

Question 4

what are commensal bacteria?

Answer 4

one species benefits and the other is unaffected.

Question 5

give an example of a commensal bacteria in the human body.

Answer 5

streptococcus oralis that can induce protection against middle ear inflammation.

Question 6

what are mutualistic bacteria?

Answer 6

both species benefit - bacteria and human/animal/plant

Question 7

give an example of a mutualistic bacteria in the human body.

Answer 7

bacteroides fragilis, bacteriodes vulgatus, and E.coli, as they produce vitamin K which helps blood clotting in humans.

Question 8

what are parasitic bacteria?

Answer 8

one species benefits and the other suffers.

Question 9

give an example of a parasitic bacteria in the human body.

Answer 9

vibrio cholerae causing cholera

Question 10

what is microbial antagonism?

Answer 10

competition between bacteria for nutrients so that there are not enough nutrients available for the growth of pathogenic bacteria.

Question 11

where can microbial antagonism take place?

Answer 11

• human vagina
• mouth
• colon

Question 12

give an example of microbial antagonism in the human vagina.

Answer 12

bacteria lactobacillus maintains a pH of 3.5-4.5 and inhibits the growth of candida albicans which can cause thrush, C.albicans cannot grow in acidic conditions.
when antibiotics are used the pH can become neutral and C.albicans are able to grow, causing thrush.

Question 13

give an example of microbial antagonism in the mouth.

Answer 13

streptococci species produce compounds which prevent growth of Gram-positive and Gram-negative cocci.

Question 14

give an example of microbial antagonism in the colon.

Answer 14

E.coli produces proteins called bacteriocins which inhibit the growth of other bacteria of the same, or closely related species, e.g. salmonella species and shigella species.

Question 15

what are opportunistic pathogens?

Answer 15

microbes that usually do not cause disease in healthy people but may become virulent with immunocompromised and unhealthy individuals.

Question 16

what is a pathogen?

Answer 16

a pathogen is a specific causative agent of disease.

Question 17

how can bacteria enter the human body?

Answer 17

• skin
• oral cavity
• lower end of small intestine and large intestine
• vagina

Question 18

what is pathogenicity?

Answer 18

pathogenicity is the ability of a parasite to gain entry to the host’s tissues and cause physiological, or anatomical change, causing a change in health and thus disease.
the ability of an organism to cause disease.

Question 19

what is infection?

Answer 19

infection is the invasion of the body by microorganisms.
infection is the multiplication of any parasitic organism in/on a host.

Question 20

what is an infectious disease?

Answer 20

an infectious disease arises when microorganisms invade a host cell; grow and/or produces substances or toxins which damage, disrupt tissues and organs, or even cause death of the host cell.

Question 21

what is contamination?

Answer 21

contamination is the presence of microbes.

Question 22

what is disease?

Answer 22

disease is a change in the state of health in which tissues/organs are disrupted or damaged.

Question 23

what is virulence?

Answer 23

virulence is the intensity/degree to which an organism causes disease.

Question 24

how do infections occur?

Answer 24

for infections to occur, microbes must enter the tissue of the host cell by a characteristic route called the portal of entry.

Question 25

what are the portals of entry?

Answer 25

• skin
• gastro-intestinal tract
• respiratory tract
• uro-genital tract

Question 26

give an example of bacteria in the gastro-intestinal tract

Answer 26

Escherichia coli (E.coli)
salmonella species
shigella vibrio - causes shigellosis.

Question 27

give an example of bacteria in the respiratory tract.

Answer 27

mycobacterium tuberculosae - causes tuberculosis
meningicoccal species - causes meningitis
bordatella pertussis - causes whooping cough.

Question 28

give an example of bacteria in the uro-genital tract.

Answer 28

chlamydia
Nesseria gonorrhoea - causes gonorrhoea
Treponema palladium - causes syphilis.
pseudomonas aeruginosa - causes UTI’s and skin infections.

Question 29

how can microorganisms damage tissues?

Answer 29

microorganisms can damage tissues via exoenzyme activies and toxins which can be aided by antiphagocytic factors to promote colonising in the host.

Question 30

what are antiphagocytic factors?

Answer 30

antiphagocytic factors are substances produced by microorganisms to help them evade being engulfed and destroyed by white blood cells.

Question 31

what is the primary infection?

Answer 31

the primary infection is the first or initial infection.

Question 32

what is a secondary infection?

Answer 32

a secondary infection occurs when the initial infection is complicated by a second infection, e.g. an infection by an opportunistic organism.

Question 33

what is an acute infection?

Answer 33

an acute infection is a severe infection that is short lived.

Question 34

what is a chronic infection?

Answer 34

a chronic infection is an infection which persists over a very long time, e.g. tuberculosis or terminal cancer.