prokaryotic microorganisms in their natural habitats - human body Flashcards
(34 cards)
what is the human microbiome?
the human microbiome is the community of microorganisms (bacteria, fungi, and viruses) that exist in/on the body.
what is the role of bacteria in the human body?
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.
what is the natural flora?
the natural flora is a population of microorganisms that infect the body without necessarily causing disease.
what are commensal bacteria?
one species benefits and the other is unaffected.
give an example of a commensal bacteria in the human body.
streptococcus oralis that can induce protection against middle ear inflammation.
what are mutualistic bacteria?
both species benefit - bacteria and human/animal/plant
give an example of a mutualistic bacteria in the human body.
bacteroides fragilis, bacteriodes vulgatus, and E.coli, as they produce vitamin K which helps blood clotting in humans.
what are parasitic bacteria?
one species benefits and the other suffers.
give an example of a parasitic bacteria in the human body.
vibrio cholerae causing cholera
what is microbial antagonism?
competition between bacteria for nutrients so that there are not enough nutrients available for the growth of pathogenic bacteria.
where can microbial antagonism take place?
- human vagina
- mouth
- colon
give an example of microbial antagonism in the human vagina.
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.
give an example of microbial antagonism in the mouth.
streptococci species produce compounds which prevent growth of Gram-positive and Gram-negative cocci.
give an example of microbial antagonism in the colon.
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.
what are opportunistic pathogens?
microbes that usually do not cause disease in healthy people but may become virulent with immunocompromised and unhealthy individuals.
what is a pathogen?
a pathogen is a specific causative agent of disease.
how can bacteria enter the human body?
- skin
- oral cavity
- lower end of small intestine and large intestine
- vagina
what is pathogenicity?
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.
what is infection?
infection is the invasion of the body by microorganisms.
infection is the multiplication of any parasitic organism in/on a host.
what is an infectious disease?
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.
what is contamination?
contamination is the presence of microbes.
what is disease?
disease is a change in the state of health in which tissues/organs are disrupted or damaged.
what is virulence?
virulence is the intensity/degree to which an organism causes disease.
how do infections occur?
for infections to occur, microbes must enter the tissue of the host cell by a characteristic route called the portal of entry.
