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biology > Cell Recognition And The Immune System > Flashcards

Cell Recognition And The Immune System Flashcards

1
Q

What are the ways the body protects itself from disease in sequence of events?

A

Skin - physical barrier

Ciliated epithelial cells and mucus - physical

Stomach acid - chemical

Phagocytosis

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2
Q

What are the immediate defences against disease?

A 
Skin 
Ciliated epithelial cells and mucus 
Stomach acid
Ear wax 
Tears, saliva and mucus (lysozymes)
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3
Q

What are is the response for t lymphocytes called ?

A

Cell mediated

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4
Q

What are the two types of defence mechanisms?

A

Non-specific

Specific

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5
Q

What types of non-specific defence mechanisms are there?

A

Physical barriers and phagocytosis

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6
Q

What types of specific defence mechanisms are there?

A

Cell mediated response

Humor al response

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7
Q

What is the difference between non-specific and specific responses?

A

Non-specific = same for every foreign material and is immediate

Specific =specific to pathogen, takes time, longer lasting

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8
Q

What types of white blood cells are there?

A

Phagocytes and lymphocytes

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9
Q

What types of phagocytes are there?

What are the differences

A

Macrophages
Larger, longer lived and antigen presenting

Neutrophils
Lobed nucleus, arrive first at sight of infection, short lived

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10
Q

What is the purpose of a loved nucleus in neutrophils?

A

Allows flexibility

To squeeze through walls of capillaries

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11
Q

Describe and explain the role of histamine in the immune response

A

Histamine released by damaged tissue

Caused swelling by making capillary walls leakier allowing more water to move via osmosis

Also allows more phagocytes to reach site of infection

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12
Q

Describe the stages of phagocytosis

A

Phagocytes migrates to site of infection via blood stream

Pathogen releases cytokines which attracts phagocytes towards it

Phagocyte attaches to pathogen via complementary receptors

Phagocyte engulfs pathogen (pseudopods form)

Forms phagosome (vesicle containing phagocyte)

Lysosomes migrate towards and fuse membranes with phagosome

Lysozymes are emptied into phagosome and hydrolyse pathogen

Soluble products absorbed into cytoplasm and antigens presented

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13
Q

What is pus?

A

Dead phagocytes and dead pathogens

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14
Q

How do our white blood cells only recognise foreign material?

A

When T and B cells are created in the bone marrow they are surrounded by only self antigens

In womb there are no outside materials

Any lymphocytes stimulate undergo programmed cell death (apoptosis) or are suppressed

Leaves only lymphocytes against foreign material

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15
Q

What is programmed cell death called?

A

Apoptosis

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16
Q

What is immunity?

A

Ability to resist infection

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17
Q

What is an antigen?

A

A molecule that stimulates an immune response

Protein or glycoprotein in cell membrane of pathogens

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18
Q

Where are T cells produced and matured ?

A

Produced
Bone marrow

Mature
Thumbs gland

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19
Q

Name the antigen presenting cells

A

Phagocytes

B cells

Abnormal and body cells

Infected cells

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20
Q

Give examples of what would trigger a cell mediated response

A

Abnormal (cancer) cells

Phagocytes containing phagosomes

Cells from same species but different organism (transplanted cells)

Infected cells (viral infection)

Toxins

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21
Q

Describe cell mediated immunity

A

T helper cell with complementary receptors bind to antigens on an antigen presenting cell

T cell is activated and divides by mitosis to produce clones

Clones differentiate to become cytotoxic, memory, helper or suppressor T cells

Cytotoxic release perforin which kills abnormal or infected cells

Memory cells are involved in the secondary immune response

T helper cells stimulated B, T and phagocytic cells

Suppressor cells stop immune reaction after infection

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22
Q

How do cytotoxic T cells kill a pathogen ?

A

Release protein called perforin which creates holes in cell membrane of abnormal or infected cells making freely permeable

Osmotic lysis

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23
Q

What T cells secrete cytokines?

A

Helper

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24
Q

What do B cells respond to?

A

Free antigens in bodily fluids (blood, tissue fluid)

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25
Q

Where are B cells produced and matured?

A

Produced
Bone marrow

Mature
Bone marrow

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26
Q

What does antigenic variability mean and what does it mean for production of B cells?

A

Pathogens have various antigens on their surface (which may change over time)

Multiple Types of B cells produced in humoral response to one pathogen

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27
Q

How many antigens will one B cell respond to?

A

Only one

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28
Q

Describe the humoral response

A

Pathogen circulates in blood along with free antigens

B cell engulfs antigens via endocytosis and presents them on its membrane

Activated T helper cell with complementary receptors will bind to antigen

Activates B cell to undergo mitosis and produce clones which differentiate into plasma and memory cells

Plasma cells produce antibodies

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29
Q

Describe the ultra structure of a plasma cell compared to a B cell

A

More Golgi apparatus (modify and secrete proteins) and mitochondria (ATP production)

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30
Q

How long do plasma cells live?

A

Few days

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31
Q

What is the function of plasma cells?

A

Produce antibodies and release them into blood stream

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32
Q

What is the function of memory cells?

A

The produce a secondary immune response

Reactivated to divide into more plasma and memory cells

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33
Q

What are antibodies?

A

Y shaped protein with a quaternary structure

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34
Q

What is an antigen?

A

A molecule in the surface of a pathogen or cell that triggers an immune response (protein, glycoprotein or lipoprotein)

35
Q

What types of polypeptide chains are antibodies made of ?

A

Heavey (long) and light (short) chains

36
Q

Name the two regions of an antibody

A

Constant and variable regions

37
Q

Where does the antigen bind to the antibody?

A

Variable region

38
Q

What hold the heavey and light chains together?

A

Disulphide bridges

39
Q

What is formed when an antibody binds to an antigen?

A

Antigen-antibody complex

40
Q

How do antibodies lead to the destruction of a pathogen?

A

Cause agglutination

Mark pathogens so more easily detected by phagocytes

Round up pathogens so that they are less spread out (engulf many at once)

41
Q

What does agglutination mean?

A

A network of antibodies and molecules contain complementary antigens bound together

42
Q

What are monoclonal antibodies?

A

Identical antibodies produced by clones of the same plasma cell

43
Q

What are polyclonal antibodies?

A

Different antibodies produced by a variety of different plasma cells

44
Q

What is the difference between poly and mono clonal antibodies?

A

Poly= antibodies to different specific antigens

Mono= antigens to specific antigen

45
Q

What are the main uses for monoclonal antibodies?

A

Medical diagnosis

Pregnancy test

Direct monoclonal antibody therapy

46
Q

What is direct monoclonal antibody therapy?

A

Antibodies to specific antigen found on cancer cells is produced

Antibodies only bind to cancer cells and block chemical signals that stimulate uncontrolled cell growth

47
Q

What is the difference between direct and indirect monoclonal antibody therapy?

A

Direct = just antibodies

Indirect= antibodies bound to cytotoxic or radioactive drug (antibodies act as vessel)

48
Q

Why are monoclonal antibodies better than conventional drugs?

A

Use less (£)

Produce less side effects

No damage to healthy cells

49
Q

How are monoclonal antibodies used in medical diagnosis ?

Why is it used?

A

Elisa test

Qualitative and quantitative data

More rapid and easier to carry out

50
Q

How do pregnancy test work?

A

HCG produced by placenta and present in urine

Antibodies to HCG are mobile on urine strip but immobile on test strip

51
Q

What does HCG stand for?

A

Human chorionic

Gonadatrophin

52
Q

What ethical concerns are there over the use of monoclonal antibodies?

A

Animal rights (índice cancer in mice)

Who should they be tested on (trials can go wrong)

Some save lives and some kill (MS)

53
Q

What are the two types of immunity ?

A

Passive
Receive antibodies from external source (no memory or plasma cells), short lived

Active
produce own plasma and memory cells which produce own antibodies

54
Q

What are the two types of active immunity?

A

Natural
Infected with pathogen and get symptoms

artificial
Exposed to attenuated pathogen, no symptoms

55
Q

What is a vaccination?

A

A preparation (inject or swallow) containing attenuated pathogen or antigens

56
Q

What does attenuated mean and how is this achieved?

A

Weakened

Killed in a way to retain antigens

Produce toxoids from toxins

Weaken pathogen

GM yeast with same antigen

57
Q

What is herd immunity?

A

When most of the population is vaccinated against a particular pathogen and so the most vulnerable are protected

58
Q

Why is herd immunity best achieved when the vaccine is given to everyone at the same time?

A

So that few people are susceptible to the diesease at once preventing spread

59
Q

Why might a vaccine not eliminate disease ?

A

Antigenic variability

People opt out of getting vaccine

Vaccine is ineffective in some

Individual have disease before vaccination

Pathogen hides from immune system

60
Q

What are the features of a successful vaccination programme?

A

Ability to store, transport and administer vaccine safely

Enough of suitable vaccine economically available

Few side effects

Able to produce herd immunity

61
Q

What are the ethical worried around vaccines?

A

Who should we test vaccines on? (Animals, people most susceptible to disease (will gain most of successful) )

Should it be compulsory

Should money be spent on expensive vaccines if disease is nearly eradicated ?

Does individual health risk outweigh benefit to whole population?

Side effects (long term)

62
Q

Why was the MMR vaccine created and what concerns are there around it?

A

Cheaper

Thought to cause autism (small sample size and not reproducible)

63
Q

Describe the difference in antibody production between the first and second immune response

A

Second produces more antibodies a lot faster

64
Q

How do vaccines protect against disease?

A

Stimulate formation of memory cells so more antibodies can be produced at a faster rate if pathogen is encountered

65
Q

Describe and explain the structure of a HIV particle

A

Attachment proteins (allow particle to bind to T helper cell for membranes to fuse)

Lipid envelope (allow membranes to fuse, structural support)

Matrix (protein layer under lipid envelope, structural support)

Capsid (made of capsimeres/proteins, contains RNA and enzymes)

RNA (contains genetic info for reproduction)

Reverse transcriptase (catalyse synthesis DNA from RNA)

66
Q

Describe how HIV replicates

A

HIV particles circulate in blood

Attach to T helper cell receptors

Membranes fuse, capsid enters cell and disintergrates

Reverse transcriptase catalyses DNA synthesis

Viral DNA diffuses into nucleus via nuclear pore

Viral DNA inserted into host DNA and is dormant for years

viral DNA activated and mRNA produced which diffuses our if nucleus via nuclear pore

Viral components synthesised using cells protein synthesis mechanisms

Components assemble and bud off of cell taking part of cell membrane with them

Occurs continually until cell dies

67
Q

Why does the HIV DNA remain dormant for years?

A

Allows for more T helper cells to contain viral DNA

divide by mitosis to produce genetically identical daughter cells

68
Q

What happens to T concentration as more HIV particles are produced?

A

Decline

69
Q

How does HIV cause disease ?

A

Damages T helper cells

Less B, T and phagocytes stimulated

Opportunistic infections occur which cause damage to cells

70
Q

What does AIDS stand for and what is it?

A

Acquired immune deficiency syndrome

Less than 200 T helper cells per mm3 of blood

71
Q

What does ELISA stand for?

A

Enzyme linked immnosorbant assay

72
Q

What can the ELISA test be used for?

A

The identify and quantify the amount and type of antibody or antigen present

73
Q

What substances can you identify using an ELISA test?

A

Drugs
Hormones
Allergens

74
Q

Describe the ELISA test (to test for the presence of HIV)

A

Add blood sample to microtitre containing HIV antigens stuck to the base

Wash out and add solution containing antibodies to HIV antibodies attached to an enzyme

Wash out and add solution containing substrate

If Individual is HIV+ then solution will change colour

75
Q

How is the ELISA test quantitative ?

A

The intensity of colour indicates concentration of substance

76
Q

Why is it important to wash the microtitre during the ELISA test?

A

The remove excess uncomplimentary antibodies and unbound antibody attaches to enzyme

Prevents false positive

77
Q

How is HIV spread (examples)

A

Via bodily fluids

Unprotected sex
Sharing needles
Blood transfusions
Via placenta (rare)

78
Q

How can HIV transmission be reduced?

A

Use of condoms

Use of clean needles

Screening blood before transfusion

79
Q

What type of virus is HIV ?

Why?

A

Antiretroviral

Synthesises DNA from RNA (usually other way around)

80
Q

What treatment is there for HIV?

A

Use of antiretroviral drugs

Inhibit reverse transcriptase and protease production

81
Q

How do antibiotics work?

A

Inhibit enzymes required for the synthesis and assembly of murein cell walls (weakens cell wall causing osmotic lysis)

Interfere with protein synthesis and metabolic pathways via enzyme inhibition

Prevent replication (inhibit DNA helicase and polymerase)

82
Q

Why don’t antibiotics work on viruses?

A

No cell structures (cell walls) or metabolic pathways to interfere with

Hide within cells

83
Q

Why don’t vaccines work on viruses?

A

Antigenic variability

Hide in cells

No memory or plasma cells

biology (28 decks)

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