Immunology

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  • Created by: Ruhab21
  • Created on: 02-10-20 23:21
Define pathogen
An organism that causes damage to it's host
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Define infectious
A disease that may be passed or transmitted from one individual to another
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Define carrier
A person who shows no symptoms when infected by a disease organism but can pass the disease to another individual
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Define disease reservoir
Where a pathogen is normally found: this may be in humans or another animal and may be a source of infection
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Define endemic
A disease which is always present at low levels in an area
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Define epidemic
Where there is a significant increase in the usual number of cases of a disease often associated with rapid disease spread.
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Define pandemic
An epidemic occurring worldwide
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Define vaccine
Uses non-pathogenic forms, products or antigens of microorganisms to stimulate an immune response
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Define antibiotic
Substances produced by microorganisms which affect the growth of other microorganisms
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Define antibiotic resistance
Where a microorganism which should be infected by an antibiotic is no longer susceptible to it
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Define vector
A living organism which transfers a disease from one individual to another
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Define toxin
A chemical produced by a microorganism which causes damage to its host
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Define antigen
A molecule that causes the immune system to produce antibodies against it. These may be individual molecules or those on the surface of cells
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What are the key organs of the immune system?
Bone marrow and thymus glands
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Describe the difference between granulocytes and agranulocytes.
Granulocytes: lobed nucleus & the granules are lysosomes for phagocytosis

Agranulocytes: spherical nucleus & produce antibodies
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What type of organism is cholera, what is its source of infection, which tissue does it affect and what symptoms are caused?
1) Gram negative bacterium
2) Source is contaminated water supplies
3) Affects the human gut lining
4) Symptoms are watery diarrhoea, severe dehydration and often death
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How is cholera transmitted, how is it prevented and what are the control methods and treatment?
TRANSMISSION:- By drinking contaminated water
PREVENTION:- treatment of water, clean drinking water and good hygiene
CONTROL METHODS & TREATMENT:- Rehydration and vaccines
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What type of organism is cholera, what is its source of infection, which tissue does it affect and what symptoms are caused?
1) Gram negative bacterium
2) Source is contaminated water supplies
3) Affects the human gut lining
4) Symptoms are watery diarrhoea, severe dehydration and often death
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How is cholera transmitted, how is it prevented and what are the control methods and treatment?
TRANSMISSION: By drinking contaminated water
PREVENTION: treatment of water, clean drinking water and good hygiene
CONTROL METHODS & TREATMENT: Rehydration and vaccines
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What type of organism is tuberculosis, what is its source, what type of tissue does it affect and what are the symptoms it presents?
1) Bacteria
2) Sourced by other infected individuals in close proximity
3) Affects lung and neck lymph nodes
4) Symptoms include coughing, chest pains and coughing up blood
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How is tuberculosis transmitted, prevented and how can it be treated?
TRANSMISSION: airborne droplets, coughing & sneezing
PREVENTION: BCG vaccination and programme
TREATMENT: A long course of antibiotics
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What type of organism is smallpox, what is its source of infection, what tissue does it affect and what symptoms does it display?
1) Virus
2) Sourced by other infected individuals in close proximity
3) Affects small blood vessels of the skin, mouth and throat
4) Symptoms include a rash and blisters
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How is smallpox transmitted and what are its preventative/treatment measures?
TRANSMISSION; airborne droplets
PREVENTION/CONTROL: now extinct due to immunisation programmes
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Suggest why were the immunisation programmes for smallpox so successful?
Smallpox had a low rate of mutation
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Why are the annual vaccination programmes for influenza ineffective?
The virus has many new strains and antigenic types so its hard to target it.
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Why are male mosquitoes not vectors of the plasmodium parasite?
Only female mosquitoes take blood meals because they need the blood for their eggs
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Outline the life cycle of the plasmodium parasite
1) Infected mosquito takes a blood meal and plasmodium enters the blood stream
2) Plasmodium enters the liver cells and mature
3) Liver cells rupture and release the parasites, which invade red blood cells and repeat the process
4) Parasites infect mosqui
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Explain some biological controls for the prevention of malaria
1) Introduce fish into the water so they can eat the aquatic larvae
2) Infect mosquito with bacterium to block plasmodium development in the mosquito
3) Sterilise male mosquitoes with X-rays so they cant provide offspring
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Explain some preventative measures to prevent malaria that are based on mosquito behaviour
1) Sleep under nets since mosquitoes feed at night
2) Place a film of oil on water to prevent larvae from piercing the surface for oxygen
3) Spray indoor walls with insecticide to kill mosquitoes when they rest after feeding
4) Treat nets with insecticide
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Why are vaccines ineffective against malaria?
Plasmodium parasite has a high mutation rate
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Describe ways in which viruses can be pathogenic
1) Production of toxic substances
2) Immune suppression
3) Cell lysis
4) Cell transformation where viral DNA integrates into the host chromosome and can cause rapid cell division
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Why are viruses outside the host cell described as inert?
They can only replicate once they've hijacked the host cell's enzyme machinery
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Describe the lytic cycle.
Viruses enter a cell and immediateky reproduce using the hosts metabolism. Once the new virions are assembled in the cytoplasm, they leave either by lysis or budding from the host cell surface
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Describe the lysogenic cycle
Virus' penetrate the cell and then integrate their nucleic acid into the host cell genome. They may remain for several cell generations and be copied. Then they enter the lytic cycle and symptoms are produced
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What type of antibiotic is penicillin and how does it work?
Bactericidal
It prevents the formation of crosslinkages in the bacterial peptidoglycan cell wall by acting as a noncompetitive inhibitor for the enzyme
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Why are viruses not affected by antibiotics?
They dont have a cell wall or metabolic pathways to disrupt
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How might the overuse of antibiotics lead to antibiotic resistance? (3 marks)
1) Bacteria have a high mutation rate so natural mutations may give them resistance to an antibiotic.
2) Overuse of bacteria leads to accidental selection of bacterial strains that are resistant
3) The frequency of the resistant allele increases
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List the natural barriers the body has as a passive immune response (7 marks)
Skin flora,
The skin,
Phagocytosis,
Blood clotting,
Mucus and Ciliated Epithelial Cells
Tear Ducts,
Saliva and the Stomach
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How does blood clotting act as a passive immune response?
If the capillaries are broken, blood clots prevent the entry of pathogens
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How do tear ducts, saliva and stomach acid act as a passive immune response?
Lysozyme in the tears and saliva hydrolyse peptidoglycan cell walls to kill bacteria. Stomach acid kills many bacteria
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How is phagocytosis a passive immune response?
1) A phagocyte engulfs a bacterium, enclosing it in a vacuole.
2) Lysosomes fuse with the vacuole and release hydrolytic enzymes to destroy the bacteria
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How do skin flora act as a passive immune response?
Bacteria and fungi found on the skin offer competition for pathogenic bacteria
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Where are B lymphocytes activated?
In the blood, spleen and lymph nodes
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Describe what occurs in the humoral response of the specific immune response.
1) A B lymphocyte with a specific receptor binds to a specific antigen on the pathogen.
2) This stimulates the B lymphocyte to undergo clonal expansion and divide by mitosis.
3) Differentiation then occurs and B lymphocyte memory cells are produced whic
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What is the protein name for antibodies?
Immunoglobulins
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What is agglutination?
The antibodies bind to a bacteria through a specific receptor and clump them together to allow phagocytes to locate and engulf bacteria
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Describe the structure of an antibody.
Y shaped heavy chains with outer light chains.
The bottom region is constant and the top region is the variable region
Since the tips of the y are complementary to the shape of the antigen
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Where are T-lymphocytes activated?
In the thymus gland
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Describe the cell mediated response (3 marks)
1) A phagocyte engulfs a pathogen and then presents its antigens on its membrane surface, becoming an antigen presenting cell.
2) A T lymphocyte detects the antigen on the antigen presenting cell and is stimulated to undergo clonal expansion by mitosis.
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Suggest what other cells can becoming antigen presenting cells apart from phagocytes?
Infected body cells and B lymphocytes.
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Describe the roles of the 3 cells T lymphocytes differentiate into.
T HELPER CELL: Produce cytokines which stimulate more phagocytic cells to migrate to the infected tissue and engulf more pathogens. Cytokines also stimulate clonal expansion of plasma B cells to secrete more specific antibodies
T MEMORY CELL: Remain dorma
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Why is the latent period in the primary reponse longer than that in the secondary reponse?
Its the period where the cell is being found
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Describe the secondary immune response
On reexpoaure, theres a very short latent period and then memory cells undergo rapid clonal expansion. Theres a rapid production of plasma B cells so a rapid and more concentrated production of antibodies. The antibodies remain at high concentrations for
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Describe passive immunity and give examples
The body recieves antibodies made by another individual for shortlived protection. The antibodies are recognised as nonself and are destroyed so no memory cells are produced.

E.g. in breast milk, through placenta to the foetus, injection
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Describe active immunity and give examples.
The individual produces their own antibodies and produces memory cells.

E.g. natural response to infection, vaccination
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Describe the different forms of vaccinations
1. Isolated antigens
2. Weakened or attenuated versions of the pathogen
3. Inactivated toxin
4. Inactive or killed pathogen
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Other cards in this set

Card 2

Front

Define infectious

Back

A disease that may be passed or transmitted from one individual to another

Card 3

Front

Define carrier

Back

Preview of the front of card 3

Card 4

Front

Define disease reservoir

Back

Preview of the front of card 4

Card 5

Front

Define endemic

Back

Preview of the front of card 5
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