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Biology a level - ocr a > Chapter 12 - Communicable Disease > Flashcards

Chapter 12 - Communicable Disease Flashcards

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1
Q

What is a pathogen

A

Disease causing microorganism

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2
Q

Different types of pathogens

A

Bacteria
Fungi
Virus
Protoctista

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3
Q

Vector definition

A

Living or non living factor that transmits a pathogen from one organism to another

Water, mosquito

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4
Q

How do viruses infect

A

They take over cell metabolism
Viral DNA gets into the host
Their genetic material is inserted into host DNA
Uses host cell to make more viruses
Viruses reproduce rapidly and evolve to adapt to their host
Bust out of cell to infect others

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5
Q

What are protoctistas

A

Eukaryotic organisms

Need a vector to transfer them to their hosts

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6
Q

2 ways bacteria can be classified

A

By their shape

By their cell walls (gram staining)

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7
Q

What are fungi

A

Eukaryotic organisms
Multicellular
Saprophytes - feed on dead + decaying matter , can be parasitic

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8
Q

How do protoctistas infect

A

Take over cells and break them open

Digest the cells contents and use it to reproduce

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9
Q

How do fungi infect

A

Digest living cells and destroy them

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10
Q

How do bacteria infect

A

Produce toxins that damage the host cells by:

  • breaking cell membranes
  • damage enzymes
  • interfere with hosts cells genetic material - can’t divide
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11
Q

Diseases caused by bacterium

A

Bacterial meningitis
Tuberculosis
Ring rot

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12
Q

Diseases caused by protoctistas

A

Potato / tomato late blight

Malaria

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13
Q

Diseases cause by fungi

A

Athletes foot
Ringworm
Black sigatoka

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14
Q

Tuberculosis affects

A

Animals - human and cattle

Damages and destroys lung tissue
Suppresses the immune system

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15
Q

Diseases caused by viruses

A

Tobacco mosaic virus
HIV AIDS
influenza

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16
Q

Bacterial meningitis affects

A

Humans (kids)

Cause blood poisoning
Rash

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17
Q

Ring rot affect

A

Potatoes and tomatoes

Gram positive bacteria
Damages leaves, tuber and fruit

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18
Q

HIV affects

A

Humans

Targets t-helper cells in immune system
Destroys immune system

Transcripts RNA to single strand of DNA
interacts with genetic material

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19
Q

Influenza

A

Animals

Kills ciliated epithelial cells in gas exchange system
Airways open to infection

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20
Q

Tobacco mosaic virus

A

Plants

Damages leaves, flowers, fruit
Stunts growth

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21
Q

Black sigatoka

A

Banana plants

Attack’s and destroys leaves
Turn black

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22
Q

Ring worm

A

Cattle

Grey white crusty areas in skin
Itchy

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23
Q

Athletes foot

A

Humans

Grows on and digests warm moist skin
Causes cracking and scaling, itchy

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24
Q

Potato blight

A

Potatoes and tomatoes

Destroys leaves, tuber, fruits

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25
Q

Malaria

A

Humans animals

Female mosquitos

Plasmodium passed on to people

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26
Q

What is direct transmission

A

Pathogen is transferred directly from one individual to another

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27
Q

Example of direct transmission

A
  • Direct contact
  • Inoculation - through cuts, break in skin
  • Ingestion
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28
Q

What is indirect transmission

A

Pathogen travels from one individual to another via an intermediate

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29
Q

Examples of indirect transmission

A

Air , water, food, another object

Fomites- inanimate objects (socks)

Vectors- mosquitos
Spores- in air and water

Soil contamination

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30
Q

How do living conditions affect disease transmission

A

Overcrowded conditions increase disease transmissions

TB - droplet infection (directly)
- remain in air (indirectly)

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31
Q

How does climate affect disease transmission

A

Increased rainfall and wind - promote spread
Damp warm conditions increase disease survival

Potato late blight - spores spread
Mosquitoes - warm - ideal for breeding

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32
Q

How social factors affect disease transmission

A

High when

Limited access to:

Healthcare
Education

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33
Q

Preventing communicable disease in plants

A 
Plant crops with space in between 
Clear fields throughly when harvesting 
Rotate crops 
Control insect vectors 
Hygiene practices - sterilising
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34
Q

How do plants recognise an attack

A

Receptors in cell membranes respond to molecules from pathogens
Stimulates release of signalling molecules
These trigger cellular responses by switching on genes
Responses = producing defensive chemicals

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35
Q

What physical defences do plants have

A

-Waxy cuticle =
barrier, stop water collecting on leaf - reduce infection transferred

-Cell walls

-produce Polysaccharide called CALLOSE =
Deposited between cell wall and plasma membrane
- harder for pathogens to enter
- at plasmodesmata = limit spread of virus between cells
- blocks sieve plates in phloem

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36
Q

What chemical defences to plants have

A

Produce antimicrobial chemicals (antibiotics)

  • kill invading pathogens, inhibit their growth - interfere with cell membranes
  • saponins / phytoalexins

Secrete chemicals toxic to insects

  • reduces plant viruses carried by insect vectors
  • cyanide
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37
Q

How does skin prevent infection

A

blocks pathogens from entering body

produces antimicrobial chemicals - lower pH , inhibiting growth of pathogen

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38
Q

How does woUnd repair prevent infection

A

Skin can repair itself by reforming a barrier against pathogen entry

  • surface is repaired by outer layer of skin cells dividing and migrating to the edges of wound
  • tissue below contracts to bring edges closer together
  • repaired using collagen fibres
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39
Q

How does expulsive reflexes prevent infection

A

Sneezing and coughing - expel foreign objects from the body (mucous membrane)

Vomiting and diarrhoea - expel contents of gut along with pathogens

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40
Q

How do fevers get rid of pathogens

A

Raise body temperature

Inhibits pathogen reproduction

Immune system works faster

41
Q

How does Mucous membranes prevent infection

A

protect the body openings that are exposed to the environment

secretes mucus that traps pathogens
contains phagocytes
contains lysozymes that destroy bacterial + fungal cell walls

42
Q

How does blood clotting prevent infection

A

blood clot is a mesh of protein fibres
take place when platelets are exposed to damaged blood vessels

plug wounds
prevent pathogen entry
stop blood loss

43
Q

How does inflammation prevent infection

A

damaged tissue activates mast cells that release histamines and cytokines

histamines
increases the permeability of the blood vessels 
- leak fluid into surroundings 
- cause swelling 
* isolate the pathogens that have entered the damaged tissue 
cause vasodiliation 
- increases the blood flow 
- makes the area hot

cytokines
- brings white blood cells to fight of pathogens

44
Q

How is phagocytosis carried out

Neutrophils and macrophages

A

Phagocytes are attracted to chemicals produced by pathogen

Phagocytes recognise the pathogen as non self

Phagocytes engulf pathogen by surrounding it with cell surface membrane until it pinches off to form vesicles called / cytoplasm moves around pathogen = phagosome

Phagosome fuses with lysosome to form = phagolysosome

Enzymes from lysosome digest and destroy pathogens

45
Q

What are the 2 types of white blood cells

A

Neutrophils - multi lobed nucleus

Macrophage

46
Q

What is an antigen

A

Molecules found on the surface of cells that trigger immune response

47
Q

How are antigen presenting cells formed

Macrophages

A

Macrophage digests everything but antigens

Combines the antigens from the pathogen surface membrane with glycoproteins in the cytoplasm called = Major Histocompatibility Complex = MHC

The MHC complex moves these antigens to the macrophages surface membrane to become = APC

48
Q

What is an APC

A

A cell that presents foreign antigens complexed with MHCs on its own cell surface membrane

49
Q

What does MHC stand for

A

Major Histocompatibilty complexes

50
Q

What do the cytokines released by phagocytes do

A

Proteins that act as messenger molecules
Informing other phagocytes that the body is under attack
Stimulating other phagocytes to move to infected area

51
Q

Why are opsonins useful chemicals in phagocytosis

A

Chemicals that bind to pathogens and tag them
So they’re more easily recognised by phagocytes

Allow phagocytes to get closer to pathogens

52
Q

Examining blood smears

What will you see

A

Red blood cells

Platelets = fragments of cells involved in blood clotting

Neutrophils

Monocytes

Lymphocyte

53
Q

Visible features of

Neutrophils

A
  • Multi lobed nucleus

- Grainy cytoplasm

54
Q

Visible features of

Lymphocytes

A
  • smaller than neutrophil

- nucleus takes up most space

55
Q

Visible features of

Monocytes

A
  • Biggest white blood cell
  • Kidney bean shaped nucleus
  • No grainy cytoplasm
56
Q

What is the structure of an antibody

A

Y shaped glycoprotein called immunoglobulin

Made of 2 identical long polypeptide chains = heavy chain
2 dental short polypeptide chains = light chain
Chains are held together by disulfide
Hinge region = allows flexibility when the antigen binds to the antibody

Binding site = variable site - gives specificity
Allows binding to receptors on immune system = constant region

57
Q

How do antibodies prevent the pathogen binding to human cells

A
  • pathogens can’t invade host cells when part of an antigen-antibody complex by blocking the cell surface receptors the pathogen needs to bind to the host
58
Q

Outline action or opsonins

A
  • antigen-antibody complex acts as an opsonise so complex is more easily recognised an engulfed by phagocytes
59
Q

Outline actions of agglutinins

A
  • anti bodies act as agglutinins - causing pathogens carrying antigen-antibody complexes to clump together - prevents from spreading - easier for phagocytes to engulf at same time
60
Q

Outline actions of antitoxins

A

Antibodies called antitoxins

Bind to toxins produced by pathogens
Prevent toxins from affecting human cells
Toxins are neutralised

61
Q

What is the function of antibodies

A
  • acts as an opsonin
  • are agglutinins
  • can neutralise toxins
  • prevent from binding to human cells
62
Q

What is active immunity

A

Immunity you get when your own immune system makes its own antibodies after being stimulated by antigens

63
Q

What are the 2 different types of active immunity

A

Natural

Artificial

64
Q

What is a example of

Natural active immunity

A

You become immune after catching a disease

You produce your own antibodies

65
Q

What is a example of

Artificial active immunity

A

When you become immune after being given a vaccination

A weakened or dead pathogen

66
Q

What is passive immunity

A

Immunity you get from being given antibodies by a different organism

67
Q

Example of

Natural passive immunity

A

A baby gaining antibodies from mothers breast milk, or placenta

Colostrum

68
Q

Example of

Artificial passive immunity

A

Immune after being injected with someone else’s antibodies

If you have tetanus, you are injected with antibodies against the tetanus toxin, from blood donations

69
Q

What are the differences between active and passive immunity

A

Active

  • long term
  • creates memory cells
  • takes time for protection to develop
  • requires exposure to antigen

Passive

  • short term
  • takes immediate effect
  • doesn’t create memory cells
  • does not need antigens
70
Q

What is cell mediated immunity

A

T lymphocytes respond to cells of an organism that have been altered

71
Q

How does cell mediation work

A

Non specific defence of phagocytosis = produces APC

The CD4 receptors on the T helper lymphocytes meets a complementary antigen on an APC and binds to it - This activated the T-helper cells in a process called CLONAL SELECTION

Then undergoes CLONAL EXPANSION the T helper cells release interleukins and divide by mitosis and differentiate into different types of T cells that carry out different functions

72
Q

What 4 things can cloned T cells do

A

Develop into T memory cells

Develop into T killer cells

They can release interleukins to increase phagocytosis

They can release interleukins to stimulate the division of B lymphocytes Increases antibody production

73
Q

Name the 4 different types of T lymphocytes

A

T killer
T memory
T helper
T regulatory

74
Q

What donT helper cells do

A

Their CD4 receptors bind to antigens on APC

Release interleukins
Which stimulate B cells
Produce different T cells
Stimulates macrophages to INGEST pathogens with antigen - antibody complex

75
Q

What do T killer cells do

A

Destroy the pathogen carrying antigens

By producing a chemical called = perforin
That kills the pathogen
By making holes in cell surface membrane
Freely permeable

76
Q

What do T memory cells do

A

Part of immunological memory

Remembrer the specific antigens
So when met again
Will divide rapidly to produce specific T killer cells
To destroy pathogen

77
Q

What do T regulator cells do

A

Suppress the immune system
From other white blood cells
Once pathogen has been eliminated
To prevent autoimmune response

Interleukins important

78
Q

What is humoral immunity

A

Produces antibodies to respond to foreign antigens

79
Q

How does humoral immunity occur

A

B lymphocytes are covered with antibodies

These antibodies join with the complementary antigens on the pathogen

The B cell engulfs and processes the antigen to become a B cell APC

T helper cells bind to the B APC = CLONAL SÉLECTION
(B cell with correct antigen is selected for cloning)

T cells produce interleukins that activate B Cells to divide by mitosis = CLONAL EXPANSION

80
Q

Why do B cells differentiate into

A

Plasma cells
B Effector cells
B Memory cells

81
Q

What do plasma cells do

Primary immune response

A

Produce antibodies to a particular antigen
Release them into circulation

Disable antigens
Act act opsonins, agglutinins, antitoxins

82
Q

What do effector cells do

A

Divide to form plasma cell clones

83
Q

What do B memory cells do

Secondary immune response

A

Provide immunological memory

Programmed to remember antigen
Enables body to respond quickly when pathogen reenters

84
Q

Why is the primary response slow

A

Antigens on pathogen active immune system
Not enough B lymphocytes to produce right antibody
Eventually will produce enough antibody - show symptoms
After exposure to antigen T + B make memory cells

85
Q

Why is the secondary response faster

A

Immune system produces stronger, faster response
B Memory divide into plasma cells = make antibodies
T Memory divide into T cells to destroy pathogen
Before symptoms show

86
Q

What is an auto immune disease

A

Response when the immune system acts against its won cells and destroys healthy tissue

Recognises “self cells” as foreign

87
Q

Rheumatoid arthritis

A

Joints

Feet, wrists

Cure = anti inflammatory , immunosuppressant, steroids

88
Q

Lupus

A

Affects skin and joints
Can attack organs

Cure = immunosuppressant, anti inflammatory, steroids

89
Q

What are the principles of vaccination

A

1) pathogen is made safe so no risk of infection
- dead, inactivated, altered, attenuated
2) small amounts of safe antigen injected into blood
3) primary immune response triggered
4) memory cells made
5) come into contact again - secondary response is quicker and stronger

90
Q

What is herd immunity

A

When most people in a community are vaccinated the disease become rare
Even people without the vaccines are unlikely to get it

Reduces the risk of an epidemic

91
Q

What are routine vaccines

A

MMR =

  • measles , mumps , rubella
  • children

Meningitis C vaccine =

  • protects against bacteria that causes Meningitis C
  • 3 months, 1 year, teenager
92
Q

Reasons for changes in vaccines and vaccination programmes

Influenza

A

Antigens on influenza surface change regularly
Forming new strains of virus

Memory cells from virus against 1 strain will not impact new strains
New vaccines are made every year that are most effective against the recent circulating viruses

93
Q

Why do possible sources of medicine need to be protected

A

Uses natural compounds
Plants, animals, microorganisms

Penicillin = fungus
Cancer drugs = soil bacteria
Alzheimer’s = daffodils

94
Q

What are personalised medicines

A

Tailored to an individuals genes

Doctor can predict how you will respond to medicine, and prescribe you the most effective using your genetic material

95
Q

What is synthetic biology

A

Uses technology to design artificial proteins, cells, microorganisms

Cancer
- destroy cancer cells while leaving body healthy

96
Q

Benefits of using antibiotics

A

Kill or inhibit growth of bacteria

Doesn’t damage human cells = isolated

97
Q

Disadvantages of antibiotics

A

Can cause severe allergic reactions

Can form antibiotic resistance
- mutations occur so they become naturally resistant, spread the advantageous gene

Prevent by not giving to small infections
Making sure the course of medicine is ended so all bacteria is killed off

98
Q

MRSA

A

Causes serious wound infection

Resistant to meticillin

99
Q

Clostridium difficile

A

Harmless bacteria in digestive system killed, expect Cdifficile

Produces cramps, fevers, diarrhoea

Biology a level - ocr a (11 decks)

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