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Biology Unit 4 > Disease 4.6 > Flashcards

Disease 4.6 Flashcards

1
Q

Describe the term pathogenic.

A

An organism that causes damage to its host.

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2
Q

What is a vector?

A

A living organism which transfers a disease from one individual to another

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3
Q

Describe the term infectious.

A

A disease that may be passed or transmitted from one individual to another.

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4
Q

Describe the term contagious.

A

A disease that can be spread by direct contact.

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5
Q

Describe what a carrier is.

A

A person who shows no symptoms when infected by a diseased organism but can pass the disease on to another individual.

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6
Q

What is a disease reservoir?

A

Where pathogen is normally found; this may be in humans or another animal and may be a source of infection.

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7
Q

What is an endemic?

A

A disease which is always present at low levels in an area.

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8
Q

What is an epidemic?

A

Where there is significant increase in the usual number of cases of a disease often associated with rapid spread.

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9
Q

What is a pandemic?

A

An epidemic occurring worldwide, or over a very wide area, crossing international boundaries and usually affecting a large number of people.

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10
Q

What is air-borne transmission / droplet infection?

A

Transmission of a disease through the air in droplets of saliva and mucus.

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11
Q

What is a toxin?

A

It is a chemical produced by a microorganism which causes damage to its host.

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12
Q

What is an antigen?

A

A substance that can induce an immune response e.g., the formation of antibodies.

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13
Q

What are antibodies?

A

Proteins produced by lymphocytes that can bind to a specific antigen and neutralise, destroy or inhibit that antigen.

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14
Q

What is a vaccine?

A

It uses non-pathogenic forms, products or antigens of microorganisms to stimulate an immune response which confers protection against subsequent infection.

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15
Q

What are antibiotics?

A

Substances produced by microorganisms which affect the growth of other microorganisms.

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16
Q

What is antibiotic resistance?

A

Where a microorganism, which should be affected by an antibiotic, is no longer susceptible to it.

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17
Q

What are antigenic types / serotypes?

A

Organisms with the same or very similar antigens on the surface. Such types are sub groups or strains of a microbial species which may be used to trace infections. They are usually identified by using antibodies from serum.

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18
Q

What is direct transmission?

A

The spread of disease from one host to another host.

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19
Q

What is indirect transmission?

A

The spread of disease from host to host by means of a vector

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20
Q

What is a mechanical vector?

A

Vector is physically contaminated with the pathogen and serves only to carry the pathogen to a new host.

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21
Q

What is a biologic vector?

A

Vector is a required part of the life cycle of the pathogen; for disease transmission to occur. The pathogen must replicate or undergo some part of its life cycle in the vector e.g., malaria.

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22
Q

What type of organism is cholera?

A

A gram negative bacteria.

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23
Q

What is the source of infection of cholera?

A

Infected faeces (in contaminated water and food).

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24
Q

What tissue does cholera affect?

A

The gut lining.

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25
Q

What is the mode of transmission of cholera?

A

Contaminated water and food.

26
Q

How is cholera prevented?

A

1: hygienic disposal of human faeces
2: Safe drinking water
3: hygienic preparation of food

27
Q

What are the control methods of Cholera?

A

1: Powerful antibiotic therapy is possible but largely by rehydration therapy.
2: Vaccine may provide temporary protection.

28
Q

What type of organism is tuberculosis?

A

Bacterium.

29
Q

What is the source of infection of tuberculosis?

A

infected people.

30
Q

What tissue is affected by tuberculosis?

A

lungs and lymphnodes in neck.

31
Q

What is the mode of transmission of tuberculosis?

A

Air-borne droplet infection i.e. sneezing / coughing.

32
Q

How is tuberculosis prevented?

A

1: School vaccination programme (BCG), age 10-14.
2: Heaf test ( inject tuberculin into skin to see if already immune).

33
Q

What are some control methods of tuberculosis?

A

1: Antibodies.
2: Less over-crowding.

34
Q

What type of organism is smallpox?

A

Variola.

35
Q

What is the source of infection of smallpox?

A

Infected humans.

36
Q

What tissue does smallpox affect?

A

Skin.

37
Q

What is the mode of transmission of smallpox?

A

Body fluids, direct contact, contagious.

38
Q

How is smallpox prevented?

A

Vacination.

39
Q

What type of organism is influenza?

A

Virus.

40
Q

What is the source of infection of influenza?

A

Infected humans.

41
Q

What tissue does influenza affect?

A

Cells lining upper respiratory tract especially the nose and throat.

42
Q

What is the mode of transmission of influenza?

A

air-borne droplet infection (Coughing, sneezing).

43
Q

How is influenza prevented?

A

Vaccination, quarantine and hygiene.

44
Q

What are the control methods of influenza?

A

Vaccines available but many antigenic types, means they aren’t always effective.

45
Q

Viruses are intracellular parasites that use a cell’s metabolic pathways to produce more virus particles. How do they cause pathogenic effects?

A

1: Cell lysis when they escape from cells to infect other cells.
2: Production of toxic substances
3: Cell transformation where they can trigger cells to become cancerous
4: Suppress the immune system (e.g. HIV).

46
Q

How is malaria produced?

A

It is a disease caused by a single-celled organism called Plasmodium. This is a protoctistan.

47
Q

What is a protoctistan?

A

A single-celled eukaryotic organism.

48
Q

What is Plasmodium?

A

It has four main species. All four species are intracellular parasites and live in liver and red blood cells in their primary host - humans.

49
Q

How is the plasmodium parasite transmitted between humans.

A

By a secondary host - the female Anopheles mosquito. As a blood sucking insect, the mosquito is a highly effective vector.

50
Q

Describe the life cycle of plasmodium.

A

1: Female Anopheles mosquito infected with the malaria parasite bites the human and transmits the infective form of the parasite (sporozoites) into the human’s blood.
2: Sporozoites enter liver cells and multiply, forming merozoites that burst out of liver cells.
3: Merozoites enter red blood cells and multiply, forming new merozoites or developing into gametocytes (reproductive form).
4: Female Anopheles mosquito bites a human infected with Plasmodium, taking up gametocytes with its blood meal.
5: Sporozoites (infective form), which develop from gametocytes, travel to the salivary glands of the mosquito.

51
Q

How is damage caused to the human?

A

1: Large numbers of liver cells being destroyed when the parasite escapes from the liver cells.
2: Large numbers of red blood cells are destroyed when the parasite escapes from the red blood cells.
3: Toxins accumulate in the blood as more and more cells are destroyed.

52
Q

What are symptoms of malaria?

A

1: Fever
2: Headaches
3: Chills

53
Q

How are mosquitos prevented from biting humans?

A

1: Mosquito nets
2: Protective clothing
3: Insect repellents

54
Q

How do mosquitoes reproduce?

A

They need water. The female mosquito lays her eggs in still water in swampy areas. The larvae hatch and breath by inserting a breathing tube through the surface film of the water. Later in the life cycle pupae develop that also breathe the same way.

55
Q

How can the vector be controlled by using drainage swamps?

A
  • Gets rid of breeding grounds
    BUT
  • Expensive
  • Destroys ecosystems
56
Q

How can the vector be controlled by spraying oil on the surface water?

A
  • Blocks breathing tubes of larvae and pupae and kills them
    BUT
  • Reduces amount of oxygen that can get into the water and this can kill other aquatic organisms.
57
Q

How can the vector be controlled by disrupting the water’s surface?

A

Larvae and pupae rely on still water to be able to breathe - disrupting the surface of the water e.g., using a fountain.

58
Q

How can the vector be controlled by spraying insecticides on the water?

A

Would kill larvae but insecticides are non-specific and would also kill other aquatic insects.

59
Q

How can the vector be controlled by using biological control?

A

Guppies that eat larvae and pupae could be introduced. But once larvae had been eaten what would they feed on.`

60
Q

How can we attack the parasite?

A

1: Anti malarial drugs and vaccines.

Biology Unit 4 (8 decks)

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