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HBS 3AB 11 The Immune Response v2
Lymphatic System
Leucocytes: white blood cells. Some secrete substances which destroy pathogens,others engulf and digest.
Lymphocytes: Approx 20-30% of all white blood cells (mainly T cells and B cells)
Phagocytes: Cells which engulf & digest mirco-organisms / cell debris. Macrophages: develop from some leucocytes. More specific.
lymph capillaries lymph vesselslymph nodes Lymph Nodes:
neck, armpits, groin & around AC
bean shaped (1 25mm) Acts as a filter containing masses of lymphoid tissue (lymphocytes,
macrophages & plasma cells)
Role of Lymphatic System Large particles (e.g. bacteria) trapped in fibre mesh and destroyed by
macrophages via Phagocytosis
Lymphocyte production increases and lymph nodes become swollen oninfection
Immune responseLymphoid Organs
Tonsils: 3 sets in pharynx Spleen: filters blood (like lymph nodes) Thymus: immunity (behind sternum)
The Immune Response
Homeostatic mechanism (very specific)
2 Part immune response1. Humoral response / antibody-mediated immunity
Special proteins (antibodies) produced from B-Cells in Lymphoid Tissue2. Cell mediated response
Special lymphocytes produced from T-Cells in Lymphoid Tissueo B and T cells are lymphocytes formed in red bone marrow but
mature in two diff. places
B cells: bone marrow T cells: Thymus
Antigens: Generally
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HBS 3AB 11 The Immune Response v2
- large molecules (proteins carbs, lipids or nucleic acids)- Whole micro organisms (virus particle & bacteria)- Part of a microorganism (cell wall, flagella)- Toxins (from bacteria)- Foreign material
Antibodies: Special Proteins (Immunoglobulins IgA, IgD, IgE, IgG, IgM) made in response to
a non-self antigen
Combines to form an antigen-antibody complex Specific active site (only one specific antigen can combine with any antibody) Released into blood / lymphAntibodies can:
Combine and inactivate the antigen by inhibiting the reactions with othercells (foreign enzyme / bacterial toxin)
Bind to surface, prevent from entering cells (viruses) Coats bacteria, more easily consumed by phagocytes Agglutination (antigens clump together) Dissolve antigen If antigen is soluble, reacts to become insoluble. (easier to be consumed)
Antibody mediated Immunity (B Cells)1. Thousands of diff types of B Cells2. When activated (sensitised) by an antigen, B Cells enlarge and divide clones3. Most clones: plasma cells which secrete a specific antibody4. Some become memory cells and spread out to all body tissues Allows faster
response in future.
Cell mediated Immunity (T Cells)1. Thousands of diff types of T Cells2. When activated (sensitised) by an antigen, T Cells enlarge and divide clones3. Most clones: specialised T Cells4. Some become memory cells and spread out to all body tissues Allows faster
response in future.
Killer T Cells
Attach to antigen and destroy itHelper T Cells
Secretes a substance that sensitises more lymphocytes Secretes a substance that attracts more macrophages Secretes a substance that enhances macrophage activity
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HBS 3AB 11 The Immune Response v2
Suppressor T Cells
Release substances that inhibit T and B cell activity, slowing down immuneresponse (when immune response is finished)
Types of Immunity Immunity: resistance to infection by invading micro organisms Immunisation: process of acquiring immunity (Natural or artificial) Passive Immunity: Individual given antibodies produced elsewhere.
Natural (from mother) or artificial (injection) Short lived but fast response
Active Immunity: Individual exposed to foreign antigen the manufacturesantibodies in defence
Natural (actually infected) or artificial (injection) Long lasting
Vaccines Vaccination: Artificial Active Immunity. (Antigen introducedindividual
produces antibodydoesnt suffer symptoms)
4 Main vaccine types:1. Micro-organisms/Viruses ofreduced virulence (attenuated): Decreased
ability to produce disease symptoms (often using recombinant DNA)
e.g. polio, TB, rubella, measles, mumps, yellow fever, flu (nasal spray)2. Dead/Inactivated micro organisms / viruses: not as prolonged
e.g. cholera, typhoid, whooping cough, flu (shot)3. Toxoids: Inactivated toxins from bacteria
e.g. diphtheria, tetanus4. Sub-unit Vaccine: fragment of organism
e.g. Hep B Delivery: syringe, ingested, nasal spray, skin patches,Risks:
Allergic reaction
Possible cross-species disease introduction (while immunising an individual itis possible that the vaccine also contains strains on another infectious disease
as a result of the cultural medium it was developed in)
Preservatives?Ethical Concerns:
How was vaccine manufactured, tested and risks associated? Manufacturing:
animal host tissue (chicken embryos - influenza, mice brains -encephalitis)
human host tissue (aborted foetus rubella) Testing:
May be tested in developing countries (exploited)
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Animal testing on: mice (other mammals), fish, amphibians,birds