diseases and immunity (topic 10) Flashcards

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1
Q

what is a pathogen

A

A disease-causing agent such as a virus or a bacterium.

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2
Q

what is a transmissible disease

A

a disease in which the pathogen can be passed from one host to another

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3
Q

what are the two ways a pathogen can be transmitted

A

directly and indirectly

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4
Q

describe pathogen transmission through direct contact

A

through body fluids such as blood and other bodily fluids

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5
Q

describe pathogen transmission through indirect contact

A

such as from the air, through water or food, contaminated surfaces or animals.

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6
Q

what is meant by bodys first line of defence

A

The body’s initial defence against disease: non-specific physical or mechnical barriers that prevent pathogens from entering the body.

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7
Q

what is meant by bodies second line of defence

A

The immune system is the second line of defence if a pathogen passes the first line of defence, enters the body and causes an infection.

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8
Q

examples and explanations of first line of defence

A

mucus- present in the respiratory tract traps dust and pathogens. (chemical barrier)
nose hair- The hairs of the nose trap dust particles and pathogens. (mechanical barrier)
stomach acid- Acid secreted in the stomach kills microorganisms in food and water. (chemical barrier)
skin- acts as a barrier, prevents entry of pathogen (mechanical barrier)

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9
Q

examples and explanations of second line of defence

A

Once a pathogen gains entry to the body, the immune system detects and destroys pathogens.
white blood cells:
phagocytes: surround and engulf pathogen in phagocytosis
lymphocytes: prodcue antibodies proteins that attach to pathogens and either kills or marks for destruction

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10
Q

what are some methods to decrease spread of diseases

A

a clean water supply
good personal hygiene
hygienic food preparation
proper waste disposal
treatment of sewage.

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11
Q

what is active immunity

A

Immunity that develops in response to a pathogen and involves the activation of memory cells.

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12
Q

what is an antigen

A

the part of a pathogen which is unique to each type of pathogen, has a complementary shape to the antibody in the body

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13
Q

what are antibodies

A

proteins produced by lymphocytes, have a complementary shape to antigens, bind
to antigens leading to direct destruction
of pathogens or marking of pathogens for
destruction by phagocytes

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14
Q

how is active immunity gained

A

after infection of the pathogen, or after vaccination

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15
Q

what are memory cells

A

A cell that forms from a lymphocyte as the immune system responds to an infection. It remains in the bloodstream and can recognise pathogens that infect after a first infection. It then differentiates to form antibody-producing lymphocytes that mount a secondary response, (bigger antibody concentration and faster response)

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16
Q

outline the process of vacciantion

A
  1. vaccine made of weakened or dead pathogen, injected into body
    2.the antigens stimulate an immune response by lymphocytes which produce antibodies
    3.memory cells also produced which means if host infected again with same pathogen, secondary immune response is mounted, destorys pathogen much faster
17
Q

what is the role of vaccination

A

controlling the spread of diseases

18
Q

explain passive immunity

A

a short-term defence against a pathogen by antibodies acquired from another individual, including across the placenta and in breast milk

19
Q

what are advantages and disadvantages of active immunity

A

-lasts a very long time, memory cells can respond to pathogen for years or maybe for rest of host life (produces memory cells)
-slow response

20
Q

what are advantages and disadvantages of passive immunity

A

-fast response, immediate
-protection only lasts weeks/ month (no memory cells produced)

21
Q

why is breast feeding important

A

because of the development of passive immunity in infants
it contains antibodies that are passed to the child. These antibodies help very young babies to fight off infections until they are older and stronger, and able to receive their first childhood vaccines.

22
Q

what is cholera

A

Bacterial infection caused by water or food contaminated with the bacterium Vibrio cholerae. (bacterium which is transmitted in contaminated water)

23
Q

what does the cholera bacterium do?

A

once bacteria in body, fo towards small intestine, inside small intestine secrete cholera toxin, which causes the intestinal cells to secrete chloride ions into the lumen of the intestine, high concentration of chloride ions causes osmotic movement of large amounts of water into the intestinal lumen
causes diarrhoea and severe dehydration and loss of ions from the blood, can lead to death

24
Q

how is diarrhoa treatd

A

oral rehydration therapy, replace lost water, drink mixture of sugar/ salts/ ions