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AS Biology > Immune System > Flashcards

Immune System Flashcards

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AP® Biology flashcards Biology 101 flashcards
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

A

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

20
Q

Memory T cells

A

In future infections of same antigen

21
Q

Antibodies

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

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

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

A

Conc of antibody does not go back down to 0

Memory cells remain

25
Q

Antigen variability

A

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
Q

Vaccinations

A

Preparation of antigen from pathogen

Injected or swallowed, depending on type

27
Q

Methods of vaccine production

A

Dead pathogen, cholera
Toxins, produce less harmful toxoids, tetanus
Weakened pathogen, polio
Genetically engineered Eukaryotes producing required antigen, Hep B

28
Q

Herd immunity

A

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
Q

Active immunity

A

Immune system responds to antigen, produces specific antibodies in response to antigen
Natural, encounter disease normally
Artificial, vaccination

30
Q

Passive immunity

A

Person given antibodies
Natural, breastmilk
Artificial, tetanus when person given antibodies for immediate effect

31
Q

Viruses

A

Not living
Acellular, no cell structure, cytoplasm or membrane
Genetic material core surrounded by capsid (made of capsomeres)
Outer envelope of lipoproteins

32
Q

HIV structure

A 
Spherical shape
Lipid, glycoproteins envelope
Cone capsid
2 identical RNA strands
Has reverse transcriptase
Retrovirus
33
Q

Methods of transmission of HIV

A

Body fluids mix

Blood transfusions, sexual intercourse, IV drug use, needle sharing, mother to baby through placenta

34
Q

HIV replication, infection

A

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
Q

AIDS

A

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
Q

HIV treatment

A

No cure, control with antiretrovirals

37
Q

MOnoclonal antibodies

A

Produced from 1 cell

Specific action, 1 antibody type produced

38
Q

Polyclonal antibodies

A

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
Q

Use of monoclonal antibodies

A

Target cancer cells with toxic drugs, does not kill healthy cells

40
Q

Monoclonal antibody function

A

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
Q

Benefits of monoclonal antibodies

A

Only a small amount of cytotoxic agent required

Fewer side effects

42
Q

Problems with monoclonal antibodies

A

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
Q

Uses of monoclonal antibodies

A 
Herceptin
Heart disease
Colon cancer
Leukaemia
Non Hodgkin lymphoma
Suppress immune system in transport operations
44
Q

Production of monoclonal antibodies

A 
Antigen inserted into GM mouse
Isolate antibody forming cells
Tumour cell + antibody forming cell = hybridoma
Antibody producing hybridoma cloned
Form monoclonal antibodies
45
Q

ELISA test

A

Enzyme linked immunosorbent assay uses antibodies and colour change to identify substance
Diagnostic tool

46
Q

ELISA test

Description

A

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
Q

Uses of the ELISa test

A

Determine serum antibody concentrations
Detecting food allergens
Serological blood test for coeliacs
Certain classes of drugs

AS Biology (29 decks)

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