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Immune System Flashcards

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1
Q

Immune system

A

Group of cells, tissues, organs, mechanisms that defend an organism against pathogens and other foreign substances

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2
Q

Immune response

A

Complex series of specific and non specific processes involving a range of cells and chemicals
If the body successfully fights infection, will respond more quickly, effectively if encountered again

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3
Q

Non specific defence mechanisms

A

Physical barriers
Chemical barriers
Phagocytosis

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4
Q

Physical barriers

A

Skin (keratinised), impermeable

Mucociliary escalator in airways

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5
Q

Chemical barriers

A

Sebum, antibacterial fatty acids, pH 5.4
Tears, lysosomes, destroys bacterial cell wall
HCl, gastric juice, lactic acid, vagina

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6
Q

Phagocytosis

A

Inflammatory response, phagocytes, chemicals
Phagocytosis, phagocytes (intracellular chemicals)
Blood clotting, haemostasis

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7
Q

Specific defence mechanisms

A 
Cell mediated response
Humoral response (body fluids)
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8
Q

Specific immune response

A

AP immunity, TB cells (lymphocytes, WBC)

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9
Q

Phagocytosis

A

Phagocyte attracted to pathogen due to chemicals released by it
Moves towards pathogen up con grad
Phagocyte has several receptors on its cell surface membrane that attach to chemicals on the pathogen surface
Lysosomes within phagocyte migrate toward phagosome, formed by engulfing bacterium
Lysosomes releases lysozyme into phagosome where bacterium is hydrolyse
Hydrolysis products of the bacterium absorbed by phagocyte

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10
Q

Humoral immunity in blood

A

Pathogen/ toxin enters bloodstream, encounters many B lymphocytes
Some B cells have appropriate molecule on surface, attach to antigens on the surface of pathogen/toxin
Attachment=> rapid div of B cell, form plasma cells, clones of original
B cells produce appropriate antibody
Some become memory cells, remain in body for long time

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11
Q

Antibody effects

A

Neutralisation
Precipitation
Agglutination
Complement reaction

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12
Q

Neutralisation

A

Antibody combines with active part of toxin, prevents it from attaching to the surface of body cell

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13
Q

Precipitation

A

2 binding sites on 1 antibody may link with 2 molecules of antigen to produce a lattice like immune complex
Soluble antigen molecules may be precipitated and more easily ingested by phagocytes

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14
Q

Agglutination

A

Similar to precipitation, 2 binding sites may bind to 2 different pathogens
Leads to phagocytosis

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15
Q

Complement reactions

A

Series of reactions which lead to lysis of pathogen or phagocytosis

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16
Q

Cellular immunity

A

T cells have highly specific receptor molecules on cell surface which attaches to antigens
Only happen if antigen on surface membrane of one of body’s own cells, next to chemical marker (Major histocompatibility complex proteins)
Invaded cell will present antigens on surface
Only T cell triggered, divides rapidly, form clone T cells

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17
Q

Types of T cell

A

Cytotoxic
Helper
Memory

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18
Q

Cytotoxic T cells

A

Destroy target cell, usually the body’s own cell infected by viruses
Involved in destruction of cancer cells

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19
Q

Helper T cells

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A

Stimulate more Tc and B cells to divide, produce plasma cells

20
Q

Memory T cells

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A

In future infections of same antigen

21
Q

Antibodies

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A

Protein called immunoglobulins
Produced by plasma cells, derived from B lymphocyte
Specific to antigen

Has antigen binding site
Variable region 
Constant region
Heavy chain
All held together by disulphide bridges
22
Q

Immunity

Primary response

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A

Primary response, initial delay. Time taken for complementary specific B cells to randomly collide with antigen, bind, divide, form plasma cells, release relevant antibodies

Antibodies destroy antigens, fewer random collisions, antibody conc falls

23
Q

Immunity

Secondary exposure

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A

Rapid secondary response due to memory cell prescence
More likely to collide with antigen. Initiate IR
More plasma cells, more antibodies

24
Q

Immunity

Between primary and secondary response

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A

Conc of antibody does not go back down to 0

Memory cells remain

25
Antigen variability
Due to genetic mutation, antigens on pathogen surface frequently change shape Multiply more rapidly, mutate quickly Slow immune response to make new antibodies Potentially risk vaccines being ineffective
26
Vaccinations
Preparation of antigen from pathogen | Injected or swallowed, depending on type
27
Methods of vaccine production
Dead pathogen, cholera Toxins, produce less harmful toxoids, tetanus Weakened pathogen, polio Genetically engineered Eukaryotes producing required antigen, Hep B
28
Herd immunity
Vaccinate significant proportion of population provides protection for unvaccinated individuals Difficult for disease to spread, fewer people to infect Important for people who cannot be vaccinated, old people, babies, immune deficient people Can lead to eradication of disease
29
Active immunity
Immune system responds to antigen, produces specific antibodies in response to antigen Natural, encounter disease normally Artificial, vaccination
30
Passive immunity
Person given antibodies Natural, breastmilk Artificial, tetanus when person given antibodies for immediate effect
31
Viruses
Not living Acellular, no cell structure, cytoplasm or membrane Genetic material core surrounded by capsid (made of capsomeres) Outer envelope of lipoproteins
32
HIV structure
``` Spherical shape Lipid, glycoproteins envelope Cone capsid 2 identical RNA strands Has reverse transcriptase Retrovirus ```
33
Methods of transmission of HIV
Body fluids mix | Blood transfusions, sexual intercourse, IV drug use, needle sharing, mother to baby through placenta
34
HIV replication, infection
Enters bloodstream, circulates HIV binds to CD4 protein on Th cell membrane Capsid fuses with membrane, RNA and enzymes enter cell Reverse transcriptase, virus RNA converted into DNA DNA inserted into Th nucleus New DNA creates mRNA with cell enzymes, contain instructions for viral proteins, RNA New visions made in cell, break out with piece of cell membrane, forming lipid envelope
35
AIDS
State of immune system infected with HIV HIV can be latent AIDS develops when virions interfere with normal Th function If Th damaged, no stimulation of B to replicate, produce antibodies Memory cells infected, destroyed Body cannot respond appropriately to infections, superinfections will kill So many Th killed, system cannot recover
36
HIV treatment
No cure, control with antiretrovirals
37
MOnoclonal antibodies
Produced from 1 cell | Specific action, 1 antibody type produced
38
Polyclonal antibodies
Humoral response, more than 1 antibody produced as microbes have more than 1 type of antigen on surface Each antigen stimulates production of specific corresponding antibody from different B cell
39
Use of monoclonal antibodies
Target cancer cells with toxic drugs, does not kill healthy cells
40
Monoclonal antibody function
Requires production of antibody that binds to antigen only on cancer cells Attach to cytotoxic agent Inject antibody cytotoxic complex into patient, target cells
41
Benefits of monoclonal antibodies
Only a small amount of cytotoxic agent required | Fewer side effects
42
Problems with monoclonal antibodies
MCA produced in mice, mice protein is foreign, immune response mounted against it Overcome by use of GM mice, produce antibodies that have similar structure to human antibodies Postcode lottery
43
Uses of monoclonal antibodies
``` Herceptin Heart disease Colon cancer Leukaemia Non Hodgkin lymphoma Suppress immune system in transport operations ```
44
Production of monoclonal antibodies
``` Antigen inserted into GM mouse Isolate antibody forming cells Tumour cell + antibody forming cell = hybridoma Antibody producing hybridoma cloned Form monoclonal antibodies ```
45
ELISA test
Enzyme linked immunosorbent assay uses antibodies and colour change to identify substance Diagnostic tool
46
ELISA test | Description
Antigens from sample attached to surface Antibody with enzyme conjugate applied over surface so it can bind to antigen Enzyme substrate added Reaction produces colour change in substrate
47
Uses of the ELISa test
Determine serum antibody concentrations Detecting food allergens Serological blood test for coeliacs Certain classes of drugs

AS Biology (29 decks)

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