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Biology Module 4 Biodiversity, Evolution And Disease > Chapter 12 Communicable Diseases > Flashcards

Chapter 12 Communicable Diseases Flashcards

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1
Q

What are the different types of pathogens?

A

Bacteria
Viruses
Fungi
Protoctista

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2
Q

What are the different modes of action used by pathogens to cause disease?

A

Pathogens can damage the host tissues directly or produce toxins which damages the host tissues.

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3
Q

How do viruses cause disease?

A

The viral genetic material is inserted into the host cells DNA. The virus then uses this host cell to make new viruses which burst out of the cell, destroying it and spreading the infection to other cells.

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4
Q

How does protoctista cause disease?

A

Protoctista take over the cells, breaking them open as the new generation emerge, however they do not take over the genetic material of the cell.
Instead the Protoctista digest and use the cell contents as they reproduce.

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5
Q

How does fungi cause disease?

A

Fungi digests living cells and destroys them.
However, some Fungi may also produce toxins that also affect the host cells.

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6
Q

How does bacteria cause disease?

A

Produce toxins that can damage host cells either by breaking down the cell membrane, inactivating enzymes or interfering with the host cells genetic material so the cell cannot divide.

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7
Q

What type of pathogen causes Tuberculosis?

A

Bacteria (affects humans and animals)

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8
Q

What type of pathogen causes Ring rot?

A

Bacteria (affects potato and tomato)
Caused by the Gram positive bacteria

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9
Q

What type of pathogen causes HIV/AIDS?
What is the effect of the pathogen?

A

Virus
The virus destroys the immune system so individuals become vulnerable to secondary infections

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10
Q

What type of pathogen causes Influenza?

A

Virus

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11
Q

What type of pathogen causes Tobacco Mosaic virus?
What is the effect of the pathogen?

A

Virus
The Tobacco plant leaves become damaged resulting in stunted growth

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12
Q

What type of pathogen causes Malaria?

A

Protoctista (carried by mosquitoes which act as vectors)

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13
Q

What type of pathogen causes Potato/ Tomato blight?
What is the effect of the pathogen?

A

Protoctista
The hyphae penetrate host cells, destroying leaves, tubers and fruit.

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14
Q

What type of pathogen causes Black Sigatoka?
What is the effect of the pathogen?

A

Fungi (affects Banana)
The fungi destroys the leaves

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15
Q

What type of pathogen causes Athletes foot?

A

Fungi

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16
Q

What is a vector?

A

Carries a pathogen spreading the disease from one organism to another

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17
Q

What type of pathogen causes Bacterial Meningitis?
What is the effect of this pathogen?

A

Bacteria
Affects the brain but can spread to the rest of the body causing blood poisoning and if left untreated death.

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18
Q

What is the effect of Influenza?

A

A viral infection which affects the Ciliated epithelial cells in the gaseous exchange system. It kills them and leaves the airways open to secondary infection.
The influenza virus can rapidly mutate meaning new strains can cause epidemics as there are no antibodies available. This means new vaccination are constantly needed to be made to protect against the disease.

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19
Q

What measures could be put in place to prevent the spread of Malaria?

A

Caused by a Protoctista which is spread via the mosquito which acts as the vector.
Preventative measures can be put in place to control the vector, using mosquito nets, insecticides and removing stagnant water to reduce breeding.

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20
Q

What is direct transmission?

A

The pathogen is transferred directly from one individual to another

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21
Q

How can pathogens be directly transmitted between animals?

A

Direct contact
Inoculation
Ingestion

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22
Q

Give some examples of direct contact

A

Kissing
Direct skin-to-skin contact
Sexual transmission
Contact with bodily fluids

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23
Q

Give some examples of Inoculation

A

Through broken skin
Animal bite
Through a puncture wound or sharing needles

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24
Q

Give some examples of ingestion

A

Consuming contaminated food or drink
Transferring pathogens to the mouth from the hands

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25
Q

What is indirect transmission?

A

A pathogen that is transmitted indirectly from one individual to another

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26
Q

How can pathogens be indirectly transmitted between animals?

A

Fomites
Droplet infection
Vectors

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27
Q

Give some examples of Fomites

A

Inanimate objects such as bedding, socks, cosmetics can transfer pathogens

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28
Q

Give some examples of droplet infection

A

Droplets of saliva and mucus which are expelled from the mouth when talking, coughing or sneezing.
These droplets can spread to healthy individuals if inhaled

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29
Q

Give some examples of vectors for animals

A

Other animals/ insects
Water

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30
Q

What factors can affect the transmission of communicable diseases in animals?

A

-Overcrowded living and working conditions
-Poor nutrition
-Compromised immune systems
-Poor disposal of waste
-Providing breeding sites for vectors
-Climate change (this can introduce new vectors and new diseases)
-Culture and infrastructure
-Socioeconomic factors- lack of trained health professionals and insufficient public warning.

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31
Q

How can pathogens be directly transmitted between plants?

A

Pathogens are spread between plants when a healthy plant comes into direct contact with a diseased plant.

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32
Q

How can pathogens be indirectly transmitted between plants?

A

Soil contamination
Vectors

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33
Q

Give some examples of soil contamination

A

Infected plants often leave pathogens or reproductive spores from Protoctista or fungi in the soil which can then infect the next crop.

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34
Q

Give some examples of vectors that transmit disease between plants

A

Wind- bacteria, viruses or spores can be carried in the wind between plants
Water- Raindrops can carry pathogens and spores
Animals- insects and birds carry pathogens and spores between plants
Humans- pathogens and spores can be transmitted by hands, clothing, farming practices and transportation.

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35
Q

What factors can affect the transmission of communicable diseases in plants?

A
  • Planting varieties of crops that are susceptible to disease
  • Overcrowding increases the risk of contact
  • Poor mineral nutrition
  • Damp, warm conditions increase the survival and spread of pathogens and spores
  • Climate change- changing conditions allow animal vectors to spread disease and changing rainfall and wind promote transmission.
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36
Q

What are physical defences in plants?

A

Barriers that prevent microorganisms from entering plant tissue

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37
Q

What are chemical defences in plants?

A

Substances secreted by the plant that kill microorganisms

38
Q

How do plants respond to attack from pathogens?

A

Receptors in the cell walls respond to chemicals that are produced when the cell wall is attacked or chemicals produced by the pathogen.
Receptors respond by releasing signalling molecules which switch on genes in the nucleus
This triggers cellular responses:
- either the production of defensive chemicals which trigger defences in unaffected cells
- or by physically strengthening cell walls.

39
Q

What are the physical defences of a plant?

A

-Waxy cuticle which acts as a barrier and prevents pathogens from coming into direct contact with epidermal cells
-Cell walls composed of cellulose
-Production of Callose

40
Q

Describe the role of Callose

A

Callose provides a physical barrier within plants to prevent the spread of a pathogen.
Callose is deposited between the cell walls and cell membranes next to infected cells, as well as depositing itself in the plasmodesmata of adjacent cells to the site of infection to prevent further spread.
Lignin can then be added to Callose in order to strengthen the barrier formed.
Callose also blocks the sieve cells of the phloem reducing spread of the pathogen around the plant.

41
Q

What are the Chemical defences of plants?

A

-Insecticides
-Insect Repellents
-Cyanide
-Antibacterial compounds
-Anti fungal compounds
-Anti-oomycetes

42
Q

How do Insecticides work in plants?

A

Plants naturally produce chemicals (such as nicotine or caffeine) to kill off insects as well as insect eggs and their larvae.

43
Q

How does insect repellent work in plants?

A

Insect repellents repel the insect vector that carry disease, for example extracts that come from lemon grass repel mosquitoes.

44
Q

How does the production of cyanide work in plants?

A

Plants can make chemicals that can be broken down to produce cyanide compounds when the plant is under attack.

45
Q

How do antibacterial compounds work in plants?

A

Plants produce antibacterial chemicals compounds that kill off bacteria such as phenols (antiseptics)

46
Q

How do anti-fungal compounds work in plants?

A

Plants produce chemicals that kill fungi by producing enzymes such as chitinase which breaks down the chitin cell wall of Fungi.

47
Q

How do Anti-oomycetes work in plants?

A

Plants can produce enzymes such as Glucanases which break down Glucan found in the cell walls of oomycetes in order to kill off oomycetes.

48
Q

What are Non-specific defences?

A

Defends against all pathogens in the same way

49
Q

What are the non-specific defences that animals use to defend against pathogens?

A

Skin
Mucous membranes
Blood clotting
Wound repair
Inflammatory response
Expulsive reflexes
Phagocytosis

50
Q

How does skin act as a non-specific defence barrier in animals?

A

Physical barrier, blocking the entry of pathogens into the body.
Chemical barrier, producing chemicals which are antimicrobial and can lower pH inhibiting the growth of pathogens.

51
Q

How do Mucous membranes act as a non-specific barrier in animals?

A

Mucous membranes protect body openings which are exposed to the environment by secreting a sticky mucus that traps pathogens and contains lysosomes which break down bacterial and fungal cell walls.

52
Q

How do expulsive reflexes act as a non-specific defence mechanism in animals?

A

Coughing and sneezing expel pathogen from mucus in the gaseous exchange system.
While vomiting expels contents of the gut along with the infected pathogens.

53
Q

How does blood clotting act as a non-specific defence barrier in animals?

A

Blood clots seal open wounds to prevent pathogenic entry. When platelets are exposed to damaged blood vessels they release convert soluble fibrinogen into insoluble fibrin which results in the formation of a fibrin mesh that traps platelets and red blood cells forming a clot.

54
Q

How does the inflammatory response act as a non-specific barrier in animals?

A

The inflammatory response results in swelling, heat, pain and redness around the damaged tissue. This is because the tissue releases molecules which increases the permeability of blood vessels forcing tissue fluid out into the surrounding area which causes swelling.
The molecules also cause vasodilation of the blood vessels, increasing blood flow to the infected area and raising the temperature preventing pathogens from reproducing. This also attracts more white blood cells to the site of damage to dispose of pathogens by phagocytosis.

55
Q

How does wound repair act as a non-specific defence mechanism in animals?

A

The skin is able to repair itself in the event of injury, the surface is repaired by the outer layer of skin cells dividing and migrating to the edges of the wound. This tissue below the wound then contracts bringing the sides closer together to be repaired by collagen fibres.

56
Q

What are phagocytes?

A

Specialised white blood cells that carry out a non-specific immune response by engulfing and destroying pathogens via phagocytosis.

57
Q

What are the two types of Phagocyte white blood cells?

A

Neutrophils and Macrophages

58
Q

What is the difference between Neutrophil and Macrophage?

A

Neutrophils are the first to respond to pathogens inside the body and move towards the wound in reponses to signals from cytokines (messenger molecules) which are released by cells at the site of the wound.
Macrophages acts as an antigen presenting cell by presenting the pathogens antigens on its surface to activate other immune system cells.

59
Q

Describe the stages of Phagocytosis

A

Pathogens produce chemicals that attract phagocytes
Phagocytes recognise the foreign antigens on the pathogen as non self
The cytoplasm of the phagocyte moves around the pathogen, engulfing it. This is made easier by the presence of opsonins.
The pathogen is then contained within a vesicle known as a phagosome in the cytoplasm of the phagocyte
A lysosome fuses with the phagosome and releases hydrolytic enzymes which break down the pathogens.

60
Q

What are opsonins?

A

Protein molecules that act as a type of antibody by attaching to the antigen on the surface of a pathogen. Therefore, enhancing phagocytosis by marking the antigen to trigger an immune response or marking dead cells for recycling.

61
Q

What cells acts as antigen presenting cells?

A

Macrophage and Dendritic cells

62
Q

What are antigen presenting cells?

A

Following phagocytosis the pathogens antigens are retained and then presented onto its protein complex on the surface of the cell.

63
Q

What are Cytokines?

A

Chemical produced by phagocytes that have engulfed a pathogen.
Cytokines act as cell signalling molecules by activating and stimulating other phagocytes to move to the site of infection.

64
Q

What is the specific immune system?

A

The Immune system ‘remembers’ the antigen after the initial response therefore leading to an enhanced reaction following susbsequent encounters

65
Q

Describe the structure of antibodies

A

-Y-shaped glycoproteins called immunoglobulins.
-Made up of two identical polypeptide chains known as the heavy chains and two shorter identical chains known as the lighter chains.
-The chains are held together by disulfide bridges -More disulfide bridges in the polypeptide chains holding their shape
-Antigen binding site is known as the variable region while the rest of the antibody is known as the constant region.

66
Q

What is the function of the variable region on an antibody?

A

The variable region on the antibody is complementary to a specific antigen of a pathogen or toxin that has triggered an immune response.

67
Q

What is the function of the hinge region on an antibody?

A

Provides the molecule with flexibility so it is able to bind with two separate antigens.

68
Q

What structure is formed when an antibody binds to an antigen?

A

Antigen-antibody complex

69
Q

Describe how antibodies are able to defend against pathogens

A

-When an antigen-antibody complex is formed, the antibody acts as an opsonin so the complex can be engulfed and digested by phagocytes
-Pathogens are unable to invade hosts cells once they are part of the antigen-antibody complex as the antibodies block the receptors that the pathogens use to bind to host cells.
-Agglutinating pathogens, antibodies can bind to two pathogen at any one time therefore causing the pathogens carrying the antigen-antibody complexes to clump together. Therefore, preventing the spread of pathogens in the body and making it easier for the phagocyte to engulf a number of pathogens at the same time.
-Acts as anti-toxins, binding to toxins produced by pathogens so they become inactive and can no longer affect human cells.

70
Q

What are T lymphocytes?

A

Originate as a precursor cell in bone marrow, however migrate to the thymus gland where they differentiate into several types of T lymphocytes.
They are involved in the specific immune response.

71
Q

What are the main types of T lymphocytes?

A

T helper cells
T killer cells
T memory cells
T regulator cells

72
Q

What is the role of T helper cells?

A

Release interleukin (type of cytokine) in a form of cell signalling which stimulates other T cells to differentiate as well as stimulating B cells to mature and develop.

73
Q

What is the role of T killer cells?

A

Destroy the pathogen carrying the antigen.
They produce a chemical, perforin, which kills the pathogen by making holes in the cell membrane so it is freely permeable.

Receptors of the T killer cells which are complementary to the antigens of the pathogen can bind releasing cytotoxins that trigger apoptosis.

74
Q

What is the role of T memory cells?

A

Part of the immunological memory, if they meet an antigen a second time, they divide rapidly forming clones of the T killer cells that destroy the pathogen.

75
Q

What is the role of T regulator cells?

A

Stop the immune response once a pathogen has been eliminated and ensures that the body recognises self antigens.

76
Q

What are the main types of B lymphocytes?

A

Plasma cells
B effector cells
B memory cells

77
Q

What is the role of plasma cells?

A

Produce antibodies to a particular antigen and release them into circulation.

78
Q

What is the role of B effector cells?

A

Divide to form plasma cell clones

79
Q

What is the role of B memory cells?

A

Part of the immunological memory.
Remember a specific antigen enabling the body to respond quickly following a second encounter.

80
Q

What is Cell mediated immunity?

A

T lymphocytes respond to the cells of an organism that have been changed in some way, for example viral infections or mutations.

81
Q

Describe the process of Cell mediated immunity

A

Receptors on some of the T helper cells are complementary to the antigens of APC.
This activates the T helper cells and produces interleukins, stimulating more T cells to divide by mitosis.
The cloned T cells may:
-develop into T memory cells
-produce interleukins stimulating phagocytosis or the division of B cells
-develop into T killer cells

82
Q

What is Humoral immunity?

A

An immune response to antigens found outside cells, the humoural response produces antibodies that are not attached to cells.

83
Q

Describe the process of Humoral immunity

A

Activated T helper cells bind to the B cell APC.
Clonal selection occurs
Interleukins produced by the activated T helper cell activates the B cells
The activated B cells divide by mitosis to produce clones of plasma cells and B memory cells.
Known as clonal expansion.
-Cloned plasma cells produce antibodies that are complementary to the antigens of the pathogen, they bind to the antigens and disable them.
-Cloned B memory cells divide to form plasma cells clone if the body is infected by the same pathogen again.

84
Q

What is colonal selection?

A

Exposure to a specific antigen stimulates the division of the cell with the appropriate antibody.

85
Q

What is the primary immune response?

A

The immune response that occurs when a pathogen enters the body for the first time, the antigens on its surface activate the immune system.
The response is slow as there are not enough B lymphocytes that make the antibody needed to bind to it, during this time the individual will show symptoms of the disease.

86
Q

What cells are formed following the primary immune response?

A

Memory T lymphocytes - remember the specific antigen
Memory B lymphocytes - record the specific antibodies needed to bind to the antigen

87
Q

What is the secondary immune response?

A

The immune response that occurs when the same pathogen enters the body again.
The response is much quicker as clonal selection happens faster.
The pathogen are killed off quickly often before symptoms of the disease can be caused.

88
Q

What cell is activated during the secondary immune response?

A

Memory B lymphocytes divide into plasma cells which produce the right antibodies.

89
Q

What type of pathogen causes Ring worm?

A

Fungi (affects mammals, including humans)

90
Q

Describe the role of the lymphatic system in the defence mechanism of the body

A

Lymph vessels contain lymph nodes consisting of lymphocytes that produce and release antibodies.
Lymph nodes can also intercept bacteria which are then engulfed by phagocytes found in the nodes.
Enlarged lymph nodes are signs that the body is fighting off infection.

Biology Module 4 Biodiversity, Evolution And Disease (3 decks)

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