The immune system Flashcards
(114 cards)
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
2
Q
How are proteins good recognition sites?
A
They have enormous variety and highly specific 3D structures
3
Q
How do lymphocytes recognise self and foreign cells?
A
Specific molecules on their surface that act as recognition sites
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)
5
Q
When are immunosuppressant drugs administered?
A
Organ transplants, to reduce chances of rejection
6
Q
How many different types of lymphocytes are there?
A
10 million
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
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
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
10
Q
How is the fetus protected from infection?
A
By the mother and the placenta
11
Q
What are the two types of white blood cells?
A
Phagocytes and lymphocytes
12
Q
Where are phagocytes found?
A
Some travel in the blood, but can move out of blood vessels into tissues
13
Q
What are the attractants for phagocytosis?
A
Chemical products that cause the phagocyte to move towards the foreign cells
14
Q
What happens when the pathogen is engulfed?
A
Forms a vesicle known as the phagosome around the pathogen
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
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
17
Q
What’s the next phase after the initial immune response?
A
The primary response that confers immunity, including the recognition of antigens
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
19
Q
What does the presence of an antigen produce?
A
Antibodies
20
Q
What is an example of a non-specific response?
A
Phagocytosis
21
Q
What is an example of a specific response?
A
The production of antibodies by lymphocytes, which provide immunity
22
Q
What are the two types of lymphocytes?
A
B cells and T cells
23
Q
Why are they called B cells?
A
They mature in the bone marrow
24
Q
What type of immunity are B lymphocytes associated with?
A
Humoral immunity (involving antibodies)
25
Why are the called T cells?
They mature in the thymus gland
26
What type of immunity are T lymphocytes associated with?
Cell-mediated immunity (involving body cells)
27
What is an antigen presenting cell?
Cells that display foreign antigens on their surface
28
What is cell-mediated response?
T lymphocytes only respond to the antigens that are presented on a body cell
29
What T lymphocytes have receptors to fit onto antigens?
T helper cells
30
What is clonal selection and expansion?
The process of finding the correct T lymphocyte that is complimentary to the antigen and the mitosis that occurs after its found
31
What does the cloning of the T cells produce?
Memory cells and plasma cells
32
What do the cloned T cells do?
Stimulate phagocytes to engulf pathogens by phagocytosis, stimulate B cells to divide and secrete their antibody and activate cytotoxic T cells
33
What do Tc cells produce that make holes in the cell-surface membrane?
A protein called perforin
34
What do Tc cells kill?
Abnormal cells and body cells infected by pathogens
35
How do holes in the membrane kill cells?
The cell membrane becomes freely permeable to all substances and the cells die as a result
36
What do Tc cells effect the most?
Viruses
37
What is humoral immunity?
Involves antibodies, which are soluble in the blood and tissue fluid of the body
38
What are the key words for humoral immunity?
Antibodies, antigen, complimentary, endocytosis and monoclonal antibodies
39
What happens when the complimentary antibody is found in the B cell to the antigen?
The antigen enters the B cell by endocytosis and get presented on its surface
40
What do Th cells do?
They bind the antigen on the APC and stimulate the division of B cells (clonal selection)
41
What does clonal expansion produce?
Plasma cells and memory cells
42
What do plasma cells do?
Secrete antibodies into the blood plasma
43
How long do plasma cells survive?
Only a few days
44
How many antibodies do plasma cells produce?
Around 2000 every second
45
What do antibodies do?
Lead to the destruction of antigens
46
What is the production of antibodies and memory cells known as?
Primary immune response
47
What are memory cells responsible for?
Secondary immune response
48
How long do memory cells live for?
Often decades
49
What do memory cells do when not in use?
Circulate in the blood and tissue fluid
50
What happens when memory cells meet the same antigen later?
They divide rapidly and develop into plasma cells and more memory cells
51
How do memory cells improve the primary immune response upon second infection?
Increased quantity of antibodies is secreted at a faster rate, ensuring a new infection is destroyed before it can cause harm
52
What are antibodies?
Proteins with specific binding sites synthesised by B cells
53
How many polypeptide chains are antibodies made up of?
4
54
What are the two types of chains in antibodies?
Two light and two heavy
55
What is an antigen-antibody complex?
Complimentary fit between an antigen and antibody
56
What is the binding site on the antibody called?
Variable region
57
What does the variable region consist of?
A sequence of amino acids that form a specific 3D shape that binds directly to a specific antigen
58
What is the constant region?
The rest of the antibody outside the variable region
59
What does the constant region do?
Binds to the B cell
60
How do antibodies lead to the destruction of antigens?
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
What are monoclonal antibodies?
Isolation and cloning of antibodies
62
What are some uses of monoclonal antibodies within medicine and science?
Targeting medication to specific cells, medical diagnosis and pregnancy testing
63
How are monoclonal antibodies used to treat cancer?
They attach to receptors on the cancer cells surface and stop the chemical signal that causes uncontrolled growth
64
What is herceptin?
A monoclonal antibody used to treat breast cancer
65
What's an advantage of direct monoclonal antibody therapy?
The antibodies are not toxic and are highly specific so cause fewer side effects than other treatments
66
What is indirect monoclonal antibody therapy?
Attachment of radioactive or cytotoxic drug to the monoclonal antibody and when the antibody attaches to the cancer cell it kills it
67
What are the benefits of monoclonal antibodies being 'magic bullets'?
They can be used in smaller doses which is cheaper and reduces the risk of side effects
68
What diseases are monoclonal antibodies used to diagnose?
Influenza, hepatitis and chlamydia
69
How can monoclonal antibodies detect prostate cancer?
Men with prostate cancer often produce more of a protein called prostate specific antigen leading to unusually higher levels in the blood
70
What do pregnancy tests detect?
The hormone human chorionic gonadotrophin (HCG)
71
How do pregnancy tests show colour?
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
What are some of the ethical issues with the use of monoclonal antibodies?
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
What are the tow forms of immunity?
Active and passive
74
What is passive immunity?
Introduction of antibodies into individuals from an outside source, no direct contact with the pathogen or antigen is necessary to induce immunity
75
What is the benefit of passive immunity?
Immunity is acquired immediately
76
What are the disadvantages of passive immunity?
The antibodies are not replaced when they are broken down, no memory cells are produced and there is no lasting immunity
77
What's an example of passive immunity?
Anti-venom given after a snake bite
78
What is active immunity?
Stimulating the production of antibodies by the individuals' own immune system, direct contact with the pathogen or its antigen is necessary
79
What are the two types of active immunity?
Natural and artificial
80
What is natural active immunity?
Results from an individual becoming infected with a disease under normal circumstances
81
What is artificial active immunity?
The basis of vaccination and involves the individual forming an immune response without them suffering the symptoms of the disease
82
What is vaccination?
Introduction of the appropriate disease antigens into the body, the intention is to stimulate an immune response
83
What do vaccines contain?
One or more types of antigen form a pathogen
84
What factors does the success of a vaccination programme depend on?
Economically available, few side effects, ability to produce, store and transport, means of administration and ability to vaccinate vast majority of population
85
What is herd immunity?
Vaccinating the vast majority of a population vulnerable
86
Why do vaccines not eliminate a disease?
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
What is antigenic variabililty?
The random mutation of pathogens, which changes the antigen shape
88
Why may individuals have objections to vaccines?
Religious, ethical or medicinal reasons
89
What are some ethical issues with the use of vaccines?
use of animals, side-effects, human trials on who, unknown health risk, compulsory, expense, individuality
90
What does HIV stand for?
Human immunodeficiency virus
91
What does HIV do?
Causes the disease acquired immune deficiency syndrome (AIDS)
92
When was HIV first diagnosed?
1981
93
What is the structure of HIV?
Lipid envelope with attachment proteins embedded, inside is the protein capsid with hold two RNA strands inside and some enzymes
94
What is one of the enzymes inside HIV?
Reverse transcriptase
95
What does reverse transcriptase do?
Catalyses the production of DNA from RNA- the reverse reaction to transcriptase
96
What does the presence of RT and its ability mean about HIV?
It's considered a retrovirus
97
How can HIV replicate?
It uses it's genetic material to instruct a host cell's biochemical mechanisms to produce the components required to make new HIV
98
What does HIV do once circulating in the bloodstream?
A protein on HIV readily binds to CD4 protein on most cells but commonly T helper cells
99
What happens once HIV has attached to CD4?
The protein capsid fuses with the cell-surface membrane, the RNA and enzymes of HIV enter the T helper cell
100
What happens to the genetic material of HIV once inside the T helper cells?
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
What happens to HIV mRNA in the Th cell?
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
How does HIV lead to AIDS?
By killing or interfering with the normal functioning of Th cells
103
How many Th cells does an uninfected person have in each mm3 of blood?
800-1200
104
How many Th cells does a person with AIDS have in each mm3 of blood?
As low as 200
105
What happens without a sufficient number of Th cells?
Cannot stimulate B cells to produce antibodies or Tc cells that kill infected cells
106
What infections do AIDS sufferers commonly develop?
Lungs, intestines, brain and eyes
107
What can AIDS sufferers experince?
Weight loss and diarrhoea
108
What does ELISA stand for?
Enzyme linked immunosorbent assay
109
What does the ELISA test do?
It uses antibodies to not only detect the presence of a protein but he quantity as well
110
How does the ELISA test work?
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
How is quantity testes in ELISA test?
The intensity of the colour
112
What can ELISA tests detect?
HIV, tuberculosis and hepatitis
113
How do antibiotics work?
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
Why are antibiotics ineffective against viruses?
There are no metabolic mechanisms or cell structures for them to disrupt, they also have a protein coat and not a murein cell wall
