Communicable Disease

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What is another name for Rubella?
German measels
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What are the two main ways that pathogens can cause disease?
1.Damaging cells (e.g. malarial parasites burst RBC) 2.Producing toxins- exotoxins released by normal living pathogen, endotoxins released when pathogen is damaged
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How does Cholera cause disease?
An exotoxin is secreted by Vibrio cholerae, which increases the secretion of chloride ions into the lumen of the intestines causing severe diarrhoea
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What are the four methods of direct transmission?
Physical contact, faecal-oral, droplet infection, spores
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What are the factors which affect the rate of transmission?
Human demographics/ Economic development/ Microbial adaptation/ Breakdown of public health measures/ Climate change/ International travel
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Name an example of a plant disease which is transmitted through a vector
Dutch elm disease- transferred by the Dutch Elm Beetle
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What are the factors contributing to the transmission of plant diseases?
Crop overcrowding/ poor mineral nutrition=reduced resistance/ Damp+warm conditions/ Climate change i.e. inc. rainfall+ winds
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How do viruses cause disease?
They invade cells+ take over their genetic machinery/cause cells to manufacture more copies of virus/host cell bursts releasing the viruses which can then infect healthy cells
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Name the two agents which cause tuberculosis
Myobacterium tuberculosis, Myobacterium Bovis
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Name the two agents which cause bacterial meningitis?
Neissreria meningitidis, Streptococcus pneumoniae
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Name the pathogen which causes ring rot
Clavibacter midniganesis
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Name the pathogen which causes black sigatoka
Mycophaerella fijensis
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How can black sigatoka transmitted?
Water splash/ Spores released into air/ contaminated shipping
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Which species does the tobacco mosaic virus infect and what are its symptoms?
Tobacco plants, 150 other species inc.tomatoes, peppers, cucumbers, petunias. Damages flowers+fruits+stunts growth
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What are the symptoms of ring worm?
Not damaging but looks unsightly and may be itchy
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What traditional practice can increase the likeliehood of catching HIV?
FGM
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Why is sub-saharan Africa the worst affected by the majority of diaseases?
Low levels of economic development/ poor healthcare/ climate-tropical an ideal breeding ground for pathogens
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How many strands of influenze are there? Which strand is most virulent?
3 (A, B and C) A is most virulent
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What is a symptom of Bacterial meningitis
A blotchy red-purple rash which doesn't dissapear when a glass is pressed against it (a symptom of septicaemia)
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What is the Malaria vector?
Anopheles (pregant) mosquitoes
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Describe the inoculation method of disease transmission?
Through break in skin (e.g. during sex), Animal bites, Puncture wound/ sharing needles
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What are Fomites?
Inanimate objects which can transfer pathogens e.g. bedding, socks, or cosmetics
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Why is soil contamination a problem?
Some pathogens mainly spores can survive the composting process and so the infection can be transferred to the next crop when the contaminated soil is used
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What does the LST CW BC acronym stand for in reference to passive plant defences?
Lignin,
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What is the function of alkaloids e.g. caffeine, nicotine, cocaine, morphine, salonine?
To give the plant a bitter taste to stop herbivores feeding on it which may transfer pathogens and damage plants making them more susceptible to attack
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What is the function of the waxy cuticle?
To prevent water collecting on the plant cells' surfaces- water is a breeding ground for pathogens
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What is tylose?
A balloon-like swelling/projection that plugs the xylem vessel to prevent the spread of pathogens around the plant
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What are terpenoids (phenols)?
Chemicals with antibacterial and antimicrobial properties.
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What do tannins do?
Inhibit attack by insects by binding to salivary proteins/digestive enzymes deactivating them- toxic to insects in large amounts
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What are defensins and what do they do?
Small cysteine rich proteins which act upon molecules in plasma membrane of pathogens- inhibiting action of transport channels
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Describe the process of necrosis.
Necrosis=deliberate cell suicide. A few cells around the site of the infection are sacrificed to save the rest of the plant. The pathogen's access to water and nutirents will be limited- stopping it spreading to the rest of the plant
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What is lysozyme? Where is it found?
An enzyme that disrupts the cell walls of bacteria by digesting peptidoglycan. Found in human tears, saliva, lysosomes
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What are interferons?
proteins produced by virus-infected body cells. They trigger the production of a second protein that inhibits viral replication by binding to mRNA coded by the virus
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What are skin flora and what is there role?
A large amount of harmless bacteria which live on the surface of the skin which prevent colonisation by other bacteria
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What is another way that colonisation of bacteria is prevented?
Sebaceous and sweat glands nwhich give the skin a pH of 3-5
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What is keratin and what is its function for primary defense?
A protein which replaces the cytoplasm in keratinocytes as they migrate to surface of skin. The keratinised layer of dead cells acts as a barrier to pathogens
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Why do exchange surfaces need to be protected by mucus membranes?
they are not able to have a thick skin barrier as this would make diffusion rate too slow. Less protected so additional mechanisms have to be put in place
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How does inactive prothrombin become activated thrombin?
with the action of thrombinase and Ca2+ ions
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What is the function of thrombin?
To convert soluble fibronogen into insoluble fibrin which allow platelets to attach and a blood clot to form
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What is another name for a platelet?
A thrombocyte
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What do damaged cells release?
Histamines
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What are chemokines?
Chemicals released by tissue cells to attract phagocytic WBC
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When do monocytes mature into macrophages?
once they are settled in an organ
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Where are T cells made? Where do they mature?
Made in bone marrow, mature in thymus gland
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What are pseudopodia?
Elongations of the cell used to enfulf microbes
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What is the function of plasma cells?
To produce antibodies (around 2000 per second). Responsible for immediate defence
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What are osponins?
Protein molecules which attach to the antigens on the surface of a pathogen- a type of antibody
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What is the function of opsonins?
They make pathogens more easily recognised by phagocytes by binding to the pathogens and tagging them
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How are monocytes recognisable on a blood smear?
they are the largest and have a large kidney-shaped nucleus
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How are lymphocytes recognisable on a blood smear?
They are smaller and their nucleus almost fills the cell
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What is the purpose of the hinge region of an antibody?
It allows the antibody to bind to more than one pathogen at once
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What are the 4 polypeptide chains of an antibody held together by? What do these bonds form between?
Disulfide bonds. 2 cysteine amino acids
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What is agglutination?
When pathogens are clumped together allowing them to be more easily recognised by macrophages. (occurs thanks to hinge region)
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How is each specific antibodies variable region different?
It has a different amino acid sequence- different primary structure- different tertiary structructure- different shape
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What is another name for an antibidy?
Immunoglobulin
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Which cells produce histamines?
Mast cells
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What does lysozyme found in the eye digest?
Peptydogylcan- i.e. bacterial cell walls
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What is another name for T killer cells? What is their function?
Cytotoxic cells. They destroy infected cells by releasing hydrogen peroxide and perforin- which makes holes in the plasma membrane causing the cytoplasm to leave
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What is the function of T helper cells?
They have CD4 receptors which bind to surface antigens on APC. Produce interleukins which stimulate the activity of B cells. Stimulate production of other T cells.
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What is the purpose of T regulator cells?
To supress the immune system once the pathogen has been overcome and ensure that the immune system is able to recognise self antigens
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How many antibodies do plasma cells produce per second?
Abouut 2000
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What do B effector cells do?
Divide to form the plasma cells
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What is cell-mediated immunity?
The coordinated action of a range of cells which responds to CHANGES INSIDE OF CELLS. It involves virus infection detection, antigen processing and mutation detection
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What is humoral immunity?
Antibody-mediated immunity which DESTROYS ACTUAL PATHOGENS. These antibodies are free in the blood so respond to CHANGES OUTSIDE OF CELLS.
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What do interleukins do?
Stimulate phagoctosis, stimulate B cells to divide
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What does humoral immunity respond to?
Bacteria, Fungi and APCs
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What normally happens to B or T cells that are specific to our own antigens?
They are destroyed during early foetal development
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Give 6 examples of autoimmune diseases
Type 1 diabetes, Rheumatoid arthitis, Lupus, Coeliac disease, haemolytic aneamia and multiple sclerosis
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What is Chemotaxis?
The movement of cells towards a particular chemical
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How long does the specific immune system take to respond?
Up to 14 days
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What is clonal selection?
The point at which the B cell with the correct antibody to overcome a particular pathogen is selected for cloning.
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What is clonal expansion?
When the activated B cell divides by mitosis to give clones of B plasma cells and B memory cells
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What is articifcial passive immunity?
Injection of antibodies (e.g. from a horse) which provides immediate immunity. Used for tetanus and diptheria-only temporary as no memory cells produced
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What is natural active immunity?
Immunity resulting from a person actually having the disease causing antibodies and memory cells to be produced
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What is artificial active immunity?
Inducing an immune response by injecting a dead or weakened form of the pathogen to stimulate an immune response
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What is natural passive immunity?
Immunity received when antibodies are transferred from mother to baby across the placenta during foetal development
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What does attenuated mean?
weakened
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What are toxoids?
Harmless versions toxins that have been altered and detoxified
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What is plasmodium an example of?
A protoctistan organism
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Why are isolated antigens sometimes used as a vaccine?
Becuase they stimulate an immune response but are unable to invade cells so can't cause disease
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What is the herd immunity threshold for measels?
83-94%
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Other cards in this set

Card 2

Front

What are the two main ways that pathogens can cause disease?

Back

1.Damaging cells (e.g. malarial parasites burst RBC) 2.Producing toxins- exotoxins released by normal living pathogen, endotoxins released when pathogen is damaged

Card 3

Front

How does Cholera cause disease?

Back

Preview of the front of card 3

Card 4

Front

What are the four methods of direct transmission?

Back

Preview of the front of card 4

Card 5

Front

What are the factors which affect the rate of transmission?

Back

Preview of the front of card 5
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