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The immune system Flashcards

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1
Q

What is immunity?

A

Preparation of the body’s defences against a second infection from the same pathogen, allowing it to be killed before it can cause any harm

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2
Q

How are proteins good recognition sites?

A

They have enormous variety and highly specific 3D structures

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3
Q

How do lymphocytes recognise self and foreign cells?

A

Specific molecules on their surface that act as recognition sites

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4
Q

What foreign bodies do the immune system need to identify?

A

Pathogens, non-self material (transplant), toxins and abnormal body cells (cancer cells)

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5
Q

When are immunosuppressant drugs administered?

A

Organ transplants, to reduce chances of rejection

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6
Q

How many different types of lymphocytes are there?

A

10 million

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7
Q

Why is there a time lag between the exposure to a pathogen and body’s defence mechanisms working?

A

Once the correct lymphocyte is found with the complimentary protein (clonal selection), clonal expansion must occur

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8
Q

How do lymphocytes recognise their own body’s cells?

A

Lymphocytes collide in fetus with own cells, the lymphocytes with complimentary proteins die

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9
Q

What is apoptosis?

A

When lymphocytes produced in the bone-marrow of adults that show an immune response to self antigens they undergo programmed cell death

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10
Q

How is the fetus protected from infection?

A

By the mother and the placenta

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11
Q

What are the two types of white blood cells?

A

Phagocytes and lymphocytes

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12
Q

Where are phagocytes found?

A

Some travel in the blood, but can move out of blood vessels into tissues

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13
Q

What are the attractants for phagocytosis?

A

Chemical products that cause the phagocyte to move towards the foreign cells

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14
Q

What happens when the pathogen is engulfed?

A

Forms a vesicle known as the phagosome around the pathogen

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15
Q

What happens after the phagosome is formed?

A

The lysosome moves towards it and fuses, the lysozymes hydrolyse the cell wall of pathogens to destroy it

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16
Q

What happens to the products of the break down of the pathogen?

A

The soluble products are absorbed into the cytoplasm of the phagocyte

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17
Q

What’s the next phase after the initial immune response?

A

The primary response that confers immunity, including the recognition of antigens

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18
Q

What is an antigen?

A

Any part of an organism that is recognised as non-self, and triggers an immune response, they are usually proteins part of the cell-surface membrane

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19
Q

What does the presence of an antigen produce?

A

Antibodies

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20
Q

What is an example of a non-specific response?

A

Phagocytosis

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21
Q

What is an example of a specific response?

A

The production of antibodies by lymphocytes, which provide immunity

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22
Q

What are the two types of lymphocytes?

A

B cells and T cells

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23
Q

Why are they called B cells?

A

They mature in the bone marrow

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24
Q

What type of immunity are B lymphocytes associated with?

A

Humoral immunity (involving antibodies)

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25
Q

Why are the called T cells?

A

They mature in the thymus gland

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26
Q

What type of immunity are T lymphocytes associated with?

A

Cell-mediated immunity (involving body cells)

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27
Q

What is an antigen presenting cell?

A

Cells that display foreign antigens on their surface

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28
Q

What is cell-mediated response?

A

T lymphocytes only respond to the antigens that are presented on a body cell

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29
Q

What T lymphocytes have receptors to fit onto antigens?

A

T helper cells

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30
Q

What is clonal selection and expansion?

A

The process of finding the correct T lymphocyte that is complimentary to the antigen and the mitosis that occurs after its found

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31
Q

What does the cloning of the T cells produce?

A

Memory cells and plasma cells

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32
Q

What do the cloned T cells do?

A

Stimulate phagocytes to engulf pathogens by phagocytosis, stimulate B cells to divide and secrete their antibody and activate cytotoxic T cells

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33
Q

What do Tc cells produce that make holes in the cell-surface membrane?

A

A protein called perforin

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34
Q

What do Tc cells kill?

A

Abnormal cells and body cells infected by pathogens

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35
Q

How do holes in the membrane kill cells?

A

The cell membrane becomes freely permeable to all substances and the cells die as a result

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36
Q

What do Tc cells effect the most?

A

Viruses

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37
Q

What is humoral immunity?

A

Involves antibodies, which are soluble in the blood and tissue fluid of the body

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38
Q

What are the key words for humoral immunity?

A

Antibodies, antigen, complimentary, endocytosis and monoclonal antibodies

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39
Q

What happens when the complimentary antibody is found in the B cell to the antigen?

A

The antigen enters the B cell by endocytosis and get presented on its surface

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40
Q

What do Th cells do?

A

They bind the antigen on the APC and stimulate the division of B cells (clonal selection)

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41
Q

What does clonal expansion produce?

A

Plasma cells and memory cells

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42
Q

What do plasma cells do?

A

Secrete antibodies into the blood plasma

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43
Q

How long do plasma cells survive?

A

Only a few days

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44
Q

How many antibodies do plasma cells produce?

A

Around 2000 every second

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45
Q

What do antibodies do?

A

Lead to the destruction of antigens

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46
Q

What is the production of antibodies and memory cells known as?

A

Primary immune response

47
Q

What are memory cells responsible for?

A

Secondary immune response

48
Q

How long do memory cells live for?

A

Often decades

49
Q

What do memory cells do when not in use?

A

Circulate in the blood and tissue fluid

50
Q

What happens when memory cells meet the same antigen later?

A

They divide rapidly and develop into plasma cells and more memory cells

51
Q

How do memory cells improve the primary immune response upon second infection?

A

Increased quantity of antibodies is secreted at a faster rate, ensuring a new infection is destroyed before it can cause harm

52
Q

What are antibodies?

A

Proteins with specific binding sites synthesised by B cells

53
Q

How many polypeptide chains are antibodies made up of?

A

4

54
Q

What are the two types of chains in antibodies?

A

Two light and two heavy

55
Q

What is an antigen-antibody complex?

A

Complimentary fit between an antigen and antibody

56
Q

What is the binding site on the antibody called?

A

Variable region

57
Q

What does the variable region consist of?

A

A sequence of amino acids that form a specific 3D shape that binds directly to a specific antigen

58
Q

What is the constant region?

A

The rest of the antibody outside the variable region

59
Q

What does the constant region do?

A

Binds to the B cell

60
Q

How do antibodies lead to the destruction of antigens?

A

Agglutination of bacterial cells, easier for phagocytes to locate them as they are less spread out within the body, they then serve as markers that stimulate phagocytes to engulf the bacterial cells to which they are attached

61
Q

What are monoclonal antibodies?

A

Isolation and cloning of antibodies

62
Q

What are some uses of monoclonal antibodies within medicine and science?

A

Targeting medication to specific cells, medical diagnosis and pregnancy testing

63
Q

How are monoclonal antibodies used to treat cancer?

A

They attach to receptors on the cancer cells surface and stop the chemical signal that causes uncontrolled growth

64
Q

What is herceptin?

A

A monoclonal antibody used to treat breast cancer

65
Q

What’s an advantage of direct monoclonal antibody therapy?

A

The antibodies are not toxic and are highly specific so cause fewer side effects than other treatments

66
Q

What is indirect monoclonal antibody therapy?

A

Attachment of radioactive or cytotoxic drug to the monoclonal antibody and when the antibody attaches to the cancer cell it kills it

67
Q

What are the benefits of monoclonal antibodies being ‘magic bullets’?

A

They can be used in smaller doses which is cheaper and reduces the risk of side effects

68
Q

What diseases are monoclonal antibodies used to diagnose?

A

Influenza, hepatitis and chlamydia

69
Q

How can monoclonal antibodies detect prostate cancer?

A

Men with prostate cancer often produce more of a protein called prostate specific antigen leading to unusually higher levels in the blood

70
Q

What do pregnancy tests detect?

A

The hormone human chorionic gonadotrophin (HCG)

71
Q

How do pregnancy tests show colour?

A

If HCG is present it attaches to an antibody and the HCG-antibody-colour complex moves along the strip until it is trapped by a different type of antibody creating a coloured line

72
Q

What are some of the ethical issues with the use of monoclonal antibodies?

A

The use of mice in the production, some deaths with their use in treating multiple sclerosis, 6 healthy volunteers experienced organ failure in drug trials 2006 raising concern

73
Q

What are the tow forms of immunity?

A

Active and passive

74
Q

What is passive immunity?

A

Introduction of antibodies into individuals from an outside source, no direct contact with the pathogen or antigen is necessary to induce immunity

75
Q

What is the benefit of passive immunity?

A

Immunity is acquired immediately

76
Q

What are the disadvantages of passive immunity?

A

The antibodies are not replaced when they are broken down, no memory cells are produced and there is no lasting immunity

77
Q

What’s an example of passive immunity?

A

Anti-venom given after a snake bite

78
Q

What is active immunity?

A

Stimulating the production of antibodies by the individuals’ own immune system, direct contact with the pathogen or its antigen is necessary

79
Q

What are the two types of active immunity?

A

Natural and artificial

80
Q

What is natural active immunity?

A

Results from an individual becoming infected with a disease under normal circumstances

81
Q

What is artificial active immunity?

A

The basis of vaccination and involves the individual forming an immune response without them suffering the symptoms of the disease

82
Q

What is vaccination?

A

Introduction of the appropriate disease antigens into the body, the intention is to stimulate an immune response

83
Q

What do vaccines contain?

A

One or more types of antigen form a pathogen

84
Q

What factors does the success of a vaccination programme depend on?

A

Economically available, few side effects, ability to produce, store and transport, means of administration and ability to vaccinate vast majority of population

85
Q

What is herd immunity?

A

Vaccinating the vast majority of a population vulnerable

86
Q

Why do vaccines not eliminate a disease?

A

Vaccines don’t work for everyone, pathogen infected before immunity develops, mutations, many varieties (can’t vaccine all of them), objections to vaccine and certain pathogens ‘hide’ from the body’s immune system

87
Q

What is antigenic variabililty?

A

The random mutation of pathogens, which changes the antigen shape

88
Q

Why may individuals have objections to vaccines?

A

Religious, ethical or medicinal reasons

89
Q

What are some ethical issues with the use of vaccines?

A

use of animals, side-effects, human trials on who, unknown health risk, compulsory, expense, individuality

90
Q

What does HIV stand for?

A

Human immunodeficiency virus

91
Q

What does HIV do?

A

Causes the disease acquired immune deficiency syndrome (AIDS)

92
Q

When was HIV first diagnosed?

A

1981

93
Q

What is the structure of HIV?

A

Lipid envelope with attachment proteins embedded, inside is the protein capsid with hold two RNA strands inside and some enzymes

94
Q

What is one of the enzymes inside HIV?

A

Reverse transcriptase

95
Q

What does reverse transcriptase do?

A

Catalyses the production of DNA from RNA- the reverse reaction to transcriptase

96
Q

What does the presence of RT and its ability mean about HIV?

A

It’s considered a retrovirus

97
Q

How can HIV replicate?

A

It uses it’s genetic material to instruct a host cell’s biochemical mechanisms to produce the components required to make new HIV

98
Q

What does HIV do once circulating in the bloodstream?

A

A protein on HIV readily binds to CD4 protein on most cells but commonly T helper cells

99
Q

What happens once HIV has attached to CD4?

A

The protein capsid fuses with the cell-surface membrane, the RNA and enzymes of HIV enter the T helper cell

100
Q

What happens to the genetic material of HIV once inside the T helper cells?

A

Reverse transcriptase converts RNA to DNA and this DNA moves into the Th nucleus, the HIV DNA creates mRNA, which contains instructions for viral proteins

101
Q

What happens to HIV mRNA in the Th cell?

A

It moves out of the nucleus through nuclear pores and uses the cells protein synthesis mechanisms to make virus which breaks away with some of the cell-surface membrane which forms the lipid envelope

102
Q

How does HIV lead to AIDS?

A

By killing or interfering with the normal functioning of Th cells

103
Q

How many Th cells does an uninfected person have in each mm3 of blood?

A

800-1200

104
Q

How many Th cells does a person with AIDS have in each mm3 of blood?

A

As low as 200

105
Q

What happens without a sufficient number of Th cells?

A

Cannot stimulate B cells to produce antibodies or Tc cells that kill infected cells

106
Q

What infections do AIDS sufferers commonly develop?

A

Lungs, intestines, brain and eyes

107
Q

What can AIDS sufferers experince?

A

Weight loss and diarrhoea

108
Q

What does ELISA stand for?

A

Enzyme linked immunosorbent assay

109
Q

What does the ELISA test do?

A

It uses antibodies to not only detect the presence of a protein but he quantity as well

110
Q

How does the ELISA test work?

A

Apply the antigen to a slide that will attach to, wash off excess, add antibody, wash off excess, add second antibody with enzyme, add colourless substrate to enzyme which will change to coloured product

111
Q

How is quantity testes in ELISA test?

A

The intensity of the colour

112
Q

What can ELISA tests detect?

A

HIV, tuberculosis and hepatitis

113
Q

How do antibiotics work?

A

Inhibit certain enzymes required for the synthesis and assembly of the peptide cross-linkages in bacterial cell walls so they cannot withstand the pressure when water enters by osmosis and bursts

114
Q

Why are antibiotics ineffective against viruses?

A

There are no metabolic mechanisms or cell structures for them to disrupt, they also have a protein coat and not a murein cell wall

Biology (22 decks)

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