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general biology I > disease spread > Flashcards

disease spread Flashcards

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1
Q

how does sickness result (2)?

A
  • part of an organism’s body malfunctions (ex: heart attack, diabetes)
  • when a pathogen invades an organism’s body and causes infection (virus, bacteria)
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2
Q

define pathogen

A

biological agent that produces disease in its host - they are usually microorganisms

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3
Q

define infection

A

when a pathogen invades and reproduces within its host, causing it damage

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4
Q

define epidemiology

A

study of distribution, cause and risk factors of health-related events (ex: infectious disease) in populations - goal is to control disease and maintain human health

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5
Q

what is important for assessing the impact of a disease (4)?

A

mode of infection transmission, how easily new hosts are infected, how well people can fight off disease/recover, environment in which the host lives

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6
Q

true or false - diseases are all the same

A

false - disease epidemics vary widely in severity and scale

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7
Q

true or false - pathogens are parasites?

A

true

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8
Q

define parasite

A

organism that lives in close association with a host and gains advantage from the relationship at the expense of the host

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9
Q

define host organism

A

organism on or in which a parasite lives and uses its ressources

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10
Q

define microorganism (microbes)

A

organism that is too small to be seen with the naked eye (requires a microscope) - most are benign, but some cause infectious diseases

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11
Q

what are 5 kinds of pathogens?

A

fungi, protozoans, helminths, bacteria, virus

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12
Q

what are fungi?

A
  • eukaryotic organisms: can grow as single celled yeasts or multicellular branched weblike structures (mycelia)
  • important sources of food and medicine (ex: mushrooms, penicillin)
  • hundreds of species live on/in human body but are harmless
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13
Q

examples of fungal pathogens

A

candida albicans - causes yeast infections when population explodes
other: athlete’s foot, fungal pneumonia, ringworm

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14
Q

what are viruses?

A
  • not really alive: mircroscopic parasites made of tiny packets of DNA and RNA wrapped in a protein coat
  • hijack cellular machinery of their hosts
  • not cell-based life form
  • infect all life forms, including bacteria
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15
Q

examples of viruses

A
  • influenza A (respiratory infection)

- rhinovirus (common cold)

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16
Q

what are bacteria?

A
  • single celled prokaryotes without membrane bound nuclei
  • between 500 and 1000 species are hosted by humans
  • most don’t cause disease, and can even aid health
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17
Q

examples of bacteria disease

A

borrelia burgdorferi - lyme disease

escherichia coli - causes deadly food poisoning

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18
Q

what are protozoans

A
  • single celled eukaryotes with a defined, membrane bound nucleus
  • can be free living or parasitic, some parasitic ones cause disease
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19
Q

examples of protozoan pathogens?

A
  • plasmodium (malaria)

- giardia lamblia (severe diarrhea)

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20
Q

what are helminths?

A
  • parasitic worms (animals, therefore multicellular and eukaryotic)
  • not all cause disease
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21
Q

examples of helminth pathogens

A
  • schistosoma mansoni: infect digestive track which causes blockages and blood loss
  • tichinosis: found in undercooked/raw meat, worm migrates from gut to muscles, including the heart
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22
Q

which type of pathogen is described as not being truly “alive”?

A

viruses

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23
Q

what type of pathogen causes malaria?

A

protozoan

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24
Q

what type of pathogen causes lyme disease?

A

bacteria

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25
Q

which microbes live in/on humans without necessarily causing disease?

A

c. albicans (fungi - yeast infections), e. coli (bacteria - food poisoning)

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26
Q

how does bacteria reproduce?

A

binary fission

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27
Q

what is binary fission?

A

a cell that replicates its DNA and splits in half, with one copy of DNA going to each of the two cells

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28
Q

how do bacteria take advantage of their host to grow/replicate?

A

use nutrients around the host cell to make new bacteria

29
Q

can bacteria reproduce in a dead organism?

A

yes, it only needs nutrients from its host

30
Q

can a virus reproduce in a dead organism?

A

no - must invade a functional host cell to produce new virus particles

31
Q

how do viruses reproduce?

A

they hijack host cell’s reproduction machinery and force it to make new virus particles

32
Q

what should you consider when deciding on the way to combat a disease?

A

consider the pathogen type (bacteria, virus, etc.)

33
Q

how can you target bacteria?

A

antibiotics - they can:

  • block synthesis of cell wall
  • interfere with bacterial ribosomes
  • inhibit RNA synthethis
  • inhibit DNA replication
  • increase permeability of cell membrane
34
Q

what is used to combat fungi, protozoans and helmiths?

A

poisons (chemicals) toxic to the pathogen but not the host - antifugals, antiprotozoals and antihelmintics

35
Q

what is used to combat viruses?

A

antivirals - disrupt function of viruses (ex: blocking receptors needed to enter host cell, disrupt viral replication) without affecting cellular function of the host

36
Q

define immune system

A

an organism’s immune system helps protect it against invading pathogens

37
Q

what is the innate immune response?

A

rapid, generic, relies on ability to identify broad classes of pathogens

38
Q

examples of innate immune response?

A

barriers, internal defenses

39
Q

acquired immune response

A

slower, specific, relies on ability to learn and remember specific pathogens

40
Q

examples of acquired immune response?

A

first exposure, subsequent exposure

41
Q

define barriers

A

physical/chemical barriers that block pathogen from entering the body

42
Q

examples of barriers

A

skin, stomach acid, digestive enzymes, mucus lining

43
Q

what is internal defense

A

white blood cells respond to pathogens that breach barriers

44
Q

examples of internal defense

A

trauma stimulating inflammatory response, white blood cells attack pathogens, pathogens release chemicals that recruit/activate other parts of the immune system (including acquired)

45
Q

what is first exposure?

A

system learns to identify pathogen - LEARNING

46
Q

examples of first exposure

A
  • immune system learns to identify specific pathogens
  • slower response than innate
  • special cells are trained to recognizen antigens of invading pathogens
  • other cells learn to produce antibodies for specific pathogen
47
Q

what is subsequent exposure

A

system remembers antigen, stimulating rapid response to infection - REMEMBERS

48
Q

examples of subsequent exposure

A
  • immune system remembers antigens
  • stimulates a more rapid response
  • specific antibodies are used swiftly
  • healthy immune system distinguishes pathogen from host’s cells and molecules (doesn’t attack itself)
49
Q

define immunity

A

immunity occurs when an organism is able to protect itself from an invading pathogen

50
Q

true or false - pathogens are infectious agents that cause disease

A

true

51
Q

true or false - all pathogens are parasidic

A

true

52
Q

which pathogen uses the cellular machinery of its host to replicate?

A

viruses

53
Q

what produces immunity to an infection

A

immune system identifies and remembers specific pathogens it has encountered

54
Q

what is the SIR model?

A

3 compartments - susceptible, infected, recovered.
every individual in a population begins as susceptible. as they get sick, they move into the infected department. as they recover, they are moved into the recovered compartment. when an epidemic is over, everyone is susceptible or recovered. arrow from S to I is how quickly individuals are infected and arrow from I to R is how quickly they recover. this model can be represented on a graph.

55
Q

three determinants of disease spread

A

population density (N), transmission rate (beta) and infectious period (L)

56
Q

define population density

A

how often individuals contact each other

57
Q

define transmission rate

A

rate of disease transmission between infected and susceptible individuals of population. depends on how often infected/susceptible come into contact, and the probability of a contact resulting in infection

58
Q

define infectious period

A

average period of time an infectious person can transmit disease to susceptible person

59
Q

what is the name of the line that shows infections over time?

A

epidemic curve

60
Q

what factors will flatten an epidemic curve?

A

lower population density, lower transmission rate, short infectious period (fast recovery)

61
Q

formula for infection

A

betaSI

62
Q

formula for recovery

A

I/L

63
Q

how do you calculate change in I

A

new infections - new recoveries

64
Q

SIR model assumtions (3)

A

1- once infected and recovered, individual has permanent immunity
2- everyone has equal chance of contacting everyone in population
3- as soon as individuals are infected, they are immediately infectious

65
Q

equation for basic reproductive number - R0

A

R0 = SbetaL

66
Q

define birth rate

A

all newborns enter the population as susceptible, at a rate depending on population size

67
Q

define death rate

A

individuals in each subpopulation die at a constant rate

68
Q

define the basic reproductive number, R0

A

average number of infections caused by a sick individual in a susceptible population

69
Q

how do you calculate critical immunization threshold (pc)

A

pc = (1 - 1/R0)

general biology I (20 decks)

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