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Flashcards in chapter 5 microbiology Deck (40):
1

whats a pathogen?

microorganism capable of causing disease

2

what does opportunistic mean?

cause disease only in compormised individuals

3

LD 50

"lethal dose" number of organisms needed to kill half the hosts cells

4

ID 50

Infectious dose, number of organisms needed to infect half the hosts

5

Communicable disease

spread from host to host. When a disease is highly communicable it is considered contagious

6

Endemic

constanly present at a low level in a specific population

7

Epidemic

occurs more frequently than usual

8

pandemic

worldwide distribution

9

stages of infectious diseases are....

incubation period, prodomal period, acute specific illness, recovery period.

10

incubation period

time between acquisition of organism or toxin and the commencement of symptoms

11

prodomal period

non specific symptoms like fever and malaise, loss of appetite

12

acute specific illness

specific symptoms start occurring

13

recovery period

illness stops and returns to normal

14

what are the determinates of pathogenicity?

transmission, adherence, invasiveness and toxigenicity

15

How are pathogens transmitted?

inhalation, ingestion, inoculation

16

name the 4 important portals of entry for pathogens

skin, respiratory tract, gastrointestinal tract, genitourinary tract

17

what are biofilms?

aggregates of interactive bacteria attached to a solid surface( including prosthesis). Up to 65% of human infections are associated with biofilms

18

what is a quorum in biofilms?

sensing molecules- biofilms secrete this which tend to repulse incoming bacteria or activate the communal bacteria to seek new bodies

19

sessile organisms in biofilms

harder to eradicate when sessile

20

planktonic biofilm organisms

easier to eradicate

21

what does collagenase and hyaluronidase to for bacteria

degrade intercellular substances allowing easy spread of bacteria through tissue

22

what does coagulase do for bacteria?

accelerates formation of fibrin clot which helps protect the organisms from phagocytes

23

what does immunoglobulin A protease do for bacteria?

kills IgA on mucosal layers

24

leukocidins role for bacteria is ...

kills neutrophilic leukocytes and macrophages

25

what is pyogenic inflammation?

pus producing

26

what is granulomatous inflammation?

granuloma forming

27

Name some contributing factors fo toxigenicity

endotoxins, fever, hypotension, activation of cascade pathway for inflammation, increased phagocytic activity, increased antibody production

28

Endotoxins

they are the cell wall of lipopolysacharides of gram negative bacteria and are not actively released from the cell. These cause fever, shock, and other general symptoms. Some biological effects are below

29

fever

due to release of IL-1 ( interleukin 1). They act on the hypothalamic temperature regulatory centre and reset it to a higher temperature

30

hypotension-

from release of bradykinin which decrease peripheral resistance

31

exotoxins

highly toxic but have good antigens and induce the synthesis of protective antibodies called antitoxins

32

what are exotoxins categorized into?

neurotoxins, enterotoxins, and miscellaneous exotoxins

33

Name some neurotoxins and what they do

tetanus toxin-blocks the release of inhibitory transmitter which leads to sustained contractions of voluntary muscles
diptheria toxin- inhibits protein synthesis in all eukaryotic cells

botulinum toxin-blocks release of acetylcholine at the synapse , producing paralysis of both voluntary and involuntary muscles

34

what do enterotoxins do?

increase cAMP which promotes cellular chloride ion excretion and inhibition of sodium ion absorption which leads to diarrhoea

35

natural defeses of the oropharynx and intestinal tract

Continuous desquamation of epithelium, presence of saliva, mucous in intestine, gastric acid, bile and proteolytic enzymes, movements of tonuge and cheek and peristalsis, immune mechanisms

36

Defense mechanisms of respiratory tract

mucous from golblet cells and mucociliary escalator, IgA in respiratory secretions, alveolar phagoytes

37

Defense of genitourinary tract

natural mucosal desquamation, vaginal secretions and cervical mucous, flushing of urine action

38

What is viraemia?

entry of the virus into the blood

39

permissive infection

virus enters host and synthesizes its componets and assembles and are released. Cell usually dies

40

non- permissive infection

transforms the host cell and integrates its DNA into the hosts genome. Cell remains alive