3.7- immunisation Flashcards

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1
Q

what is immunisation?

A

process where a person develops immunity to a disease-causing organism

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2
Q

what is active immunity?

A

the protection gained as a result of the person’s body producing its own antibodies

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3
Q

how does a person gain immunity by natural means?

A

through immunological memory

if initial exposure to an infection is survived, subsequent exposure to the same antigen at a layer date results in the secondary response, preventing the disease from recurring

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4
Q

what does a vaccine use?

A

uses antigens from infectious pathogens to create memory cells

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5
Q

what can the antigens used in a vaccine be?

A

inactivated pathogen toxins

dead pathogens

parts of pathogens

weakened pathogens

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6
Q

3 ways vaccines are introduced into the body

A

injection

ingestion

nasal spray

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7
Q

what is an antigen usually mixed with?

A

adjuvant

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8
Q

what is an adjuvant?

A

chemical substance

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9
Q

what 2 things does the changed antigen cause in each vaccination case?

A

production of B and T cells

the formation of antibodies but does not cause the disease

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10
Q

what do some B and T cells persist in the body as and what do they do?

A

memory cells

initiate secondary response if person is exposed to the normal disease-causing antigen at a later date

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11
Q

when does herd immunity occur?

A

when a large percentage of the population is immunised

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12
Q

how are non immune individuals protected in herd immunity?

A

there is a lower probability they will come into contact with infected individuals

disrupts normal chain of infection

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13
Q

what makes herd immunity effective?

A

only a minority of the population can be left unvaccinated

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14
Q

what is the herd immunity threshold?

A

the percentage of immune individuals in a population above which a disease no longer manages to persist

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15
Q

3 factors that alter the value of the herd immunity threshold

A

virulence of pathogen (capacity for causing disease)

vaccines effectiveness

density of population

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16
Q

2 difficulties surrounding mass vaccination

A

poverty in developing world

rejection of a percentage of the population in the developed world

17
Q

when does a persons vaccination schedule usually begin in the UK?

A

2 months

18
Q

5 vaccinations you receive in the UK

A

influenza

whooping cough

tetanus

poliomyelitis

diphtheria

19
Q

why might herd immunity be compromised in developed countries?

A

if parents believe adverse publicity and refuse to have their children vaccinated

20
Q

what happens within a population of pathogenic microorganisms?

A

new strains arise continuously by mutation

21
Q

what are the new strains described as showing and why?

A

antigenic variation

if they have antigens on their surface that are different from the original strain

22
Q

what are the new strains of pathogens showing antigenic variation said to be and why do they work?

A

genetically and immunologically distinct from parent strain

succeed as it employs a selective advantage

23
Q

what effect do new antigens have on the influenza virus?

A

enable it to avoid effects of the human body’s immunological memory

24
Q

how do new antigens disabling immunological memory allow influenza reinfect a person?

A

new antigens are not recognised by their memory cells