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BIOLOGY OCR A > 4.1 Communicable Diseases > Flashcards

4.1 Communicable Diseases Flashcards

Prevention and the Immune System (64 cards)

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1
Q

What are communicable diseases?

A

A disease caused by pathogens that can be passed from one organism to another

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2
Q

What are vectors in relation to disease

A

Organisms which carry pathogens from one organism to another eg. mosquitos

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3
Q

What are bacteria, how are they classified

A

Prokaryotes
classified by their basic shapes and cell walls (react differently to gram staining, Gram positive or gram negative)

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4
Q

What are viruses

A

Non-living infectious agents
Invade living cells, their genetic material takes over their host cell, where they divide rapidly

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5
Q

What are viruses that attack bacteria called

A

Bacteriophages
Take over bacterial cells and use them to replicate, destroying the bacteria
These can be used to identify and treat some diseases

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6
Q

What are Protoctista

A

Eukaryotic organisms that use people or animals as host organisms, may need vectors

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7
Q

What are fungi

A

Eukaryotic organisms, most feeding on dead or decaying matter, but some feed on live plants and animals
They can quickly kill the plant as they stop them from photosynthesising
Reproduce via spores million of spores which can spread huge distances

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8
Q

Explain how viruses work

A

Viruses attack to a host cell and insert viral nucleic acid, replicate inside the host cell, leading to synthesis of viral proteins. Lysis of the virus then occurs, destroying the host cells and infecting other cells.

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9
Q

Explain how Protoctista work

A

Take over cells, but not the genetic material, they digest and use the cell contents as they reproduce.

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10
Q

Explain how fungi work

A

digest living cells and destroy them

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11
Q

Explain how toxins work

A

Produced by most bacteria, poison or damage the host cell, causing disease

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12
Q

Why are plant disease a big concern

A

Crop failure - starvation, struggling economies, loss of jobs
Ecosystems threatened

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13
Q

Ring Rot:

A

Impacts potatoes, tomatoes and aubergines
Damages leaves, tubers and fruit
No cure
If ring rot impacts a field, it cannot be used for 2 years

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14
Q

Tobacco mosaic virus (TMV)

A

Impacts tobacco plaints and 150 others
Damages leaves, flowers and fruits, stunting growth and reducing yield
No cure - resistant crops

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15
Q

Potato blight

A

Caused by a fungus like Protoctista
Destroying leaves, tubers and fruit
No cure - resistant crops, careful management and chemicals reduce risk

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16
Q

Black sigatoka

A

Impacts bananas
Caused by a fungus - attacks and destroys leaves
Causes leaves to turn black, reduction in yield
No cure - Resistant strains, fungicides

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17
Q

Tuberculosis

A

Damages and destroys lung tissue, suppresses immune system
Curable by antibiotics, preventable by improving living standards and vaccination

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18
Q

Bacterial meningitis

A

Bacterial infection of the protective membranes on the brain, can spread to the rest of the body and cause septicaemia
Antibiotics cure the early disease
Vaccines can protect against some forms of meningitis

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19
Q

HIV/AIDS

A

HIV (human immunodeficiency virus) causes AIDS (acquired immunodeficiency syndrome), targets T helper cells, destroys immune system and leaves person vulnerable to disease
Passed via bodily fluids

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20
Q

Influenza (flu)

A

Viral infection of ciliated epithelial cells in lungs
Airway is open to secondary infection like pneumonia
Can be fatal to vulnerable
Mutate regularly usually small - major change in antigens = flue epidemic

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21
Q

Malaria

A

Caused by Protoctista Plasmodium
Carried by vectors (mosquitos)
Plasmodium reproduces in female mosquito, feeds on humans, Plasmodium passed onto people, invading RBC and organs
People are weak and vulnerable to other infections

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22
Q

How is the spread of Malaria managed

A

Mosquitos destroyed by insecticides
Removal of standing water where they breed
Mosquito nets, window and door screens, long sleeved clothes

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23
Q

Ring Worm

A

fungal disease
Causes itchy circular infections
Antifungal creams

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24
Q

Athletes foot

A

Fungal disease, form of ring worm
Digests warm, moist skin between toes
Causes itchy cracking and scaling
Antifungal creams

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25
Direct transmission - animals
Direct contact - skin to skin, bodily fluids Inoculation - break in skin, animal bite/puncture wound, sex Ingestion - contaminated food or drink, transfer of pathogens from mouth to hands
26
Indirect transmission - animals
Fomites - inanimate objects Droplet infection (inhalation) - droplets of saliva and mucus Vectors - animals and water transports disease from one host to another
27
Factors affecting transmission of communicable disease in animals
Overcrowding Poor nutrition - contaminated water Compromised immune system Poor waste disposal - breeding ground for vectors Climate change - spread of animal vectors to new areas Culture and infrastructure Socioeconomic factors - lack of trained health workers
28
Direct transmission - plants
direct contact between healthy plant and diseased
29
Indirect transmission - plants
Soil contamination - reproductive spores of pathogens left in soil Vectors - Wind, water, animals, humans
30
Factors affecting transmission of communicable disease in plants
Crops that are vulnerable Overcrowding Poor mineral nutrition - reduces resistance Damp, warm conditions - increases survival and spread of pathogens Climate change - increased rainfall and wind, changing climate allows spread of animal vectors to new areas
31
Physical defence in plants
Cell receptors in cell membrane recognise pathogen Pathogenic enzymes break down cell walls, products are recognised Signalling molecules alert nucleus Callose and lignin are made to strengthen cell wall - deposited in cell wall and plasmodesmata - blocking off infected cell from healthy Defensive chemicals alert other cells, and some attack pathogen
32
Chemical defence in plants
Insect repellents Insecticides Antibacterial compounds Antifungal compounds Anti-oomycetes General toxins
33
Non specific human defences
Skin Mucous membrane Lysozymes Expulsive reflexes Blood clotting and wound repair Fever
34
Explain the formation of a blood clot Blood Clotting Cascade
Damaged tissue - Platelets activated - release an enzyme - enzyme along with a cofactor catalyse the reaction of a protein (Prothrombin) into an enzyme (thrombin) - this catalyses the reaction of fibrinogen into fibrin which holds the platelets together, forming a clot
35
How does the skin protect against pathogens
Top layer made from dead cells - viruses cannot reproduce Constant removal of dead cells - microorganisms cannot live here Dry - bacteria cannot live here Areas not covered by skin are covered by a mucus membrane
36
Inflammatory response
Mast cells release histamines and cytokines Histamines - Blood vessels dilate, localised heat - prevents pathogens reproducing, denatures pathogenic enzymes. (Fever) Blood vessels are more leaky - excess tissue fluid - causing swelling Cytokines - attract WBC to site
37
Explain Phagocytosis - neutrophil
Pathogens produce chemicals that attract phagocytes Phagocytes recognise non body cells Phagocyte engulfs pathogen, enclosing it in a phagosome Phagosome combines with a lysosome (phagolysosome) Enzymes from the lysosome digest and destroy pathogen
38
Macrophage phagocytosis
Macrophage carries out phagocytosis Antigens from the digested pathogen combine with the glycoproteins in the cytoplasm, forming a Major histocompatibility complex (MHC) MHC then moves to macrophage's cell surface membrane, becoming an antigen presenting cell (APC) This triggers a specific immune response
39
Chemicals helpful to phagocytosis:
Cytokines - Cell signalling molecules, alerting other phagocytes they move to site of infection Opsonins - Bind to pathogens and tag them so they can be recognised by phagocytes Eg. Immunoglobulin G, Immunoglobulin M
40
Blood cells under a microscope Monocyte Neutrophil Platelet Erythrocyte
Monocyte - large circular nucleus Neutrophil - multilobed nucleus Platelet - small dots Erythrocyte - Grey circle with lighter grey circle in middle
41
Antibody structure:
Y shaped glycoproteins called immunoglobulins Bind to specific antigen on pathogen (antigen-antibody complex)- antibody binding site = variable region Rest of antibody is the constant region Two identical long polypeptide (heavy) chains, two shorter identical (light) chains. Chains held together by disulphide bridge hinge region is flexible
42
How do antibodies defend the immune system
Antigen-antibody complex tags pathogen (Opsonin) Pathogens can not invade host cell due to complex Agglutinins - other antigen-antibody complexes clump together Anti-toxins
43
T lymphocytes
Mature in Thymus gland T helper - Produce interleukins (Cytokine (cell signalling ), stimulates activity of B cells, production of T cells and attracts macrophages T killer - destroy the pathogen - T memory - Immunological memory, divide rapidly upon meeting an antigen T regulator - Suppress immune system once pathogen has been eliminated, prevents attack on body cells
44
B lymphocytes
mature in bone marrow Plasma cells - produce antibodies, does not last very long B effector cells - divide to form plasma cells clones B memory cells - Live for a very long time immunological memory, enable rapid response
45
Cell mediated immunity
APCs from macrophages phagocytosis receptors on T helpers fit the antigens, become activated and produce interleukins, stimulating more T cells to divide via mitosis Cloned T cells may Develop into T memory Produce interleukins stimulating phagocytosis Produce interleukins stimulate B cell division Stimulate development of T killer cells
46
Humoral immunity
Response to antigens found outside the cells Activated T helper cells bind to B cell APC (clonal selection) B cell with correct antibody is selected for cloning Interleukins produced by T helper cells activate B cell Activated B cell divides via mitosis (clonal expansion) Cloned cells then either carry out primary or secondary immune response
47
Contrast primary immune response and secondary immune response
Cloned plasma cells produce antibodies, disabling antigens/act as opsonin/agglutinins - Primary immune response Some cloned cells develop into B memory cells - secondary immune response
48
What is an autoimmune disease?
Immune system attacks healthy body tissue - not communicable May be genetic or T regulators not working well or body responds abnormally to pathogen
49
What is the treatment for an autoimmune disease?
Immunosuppressants - prevents immune system working
50
Example of autoimmune disease
Rheumatoid arthritis - Impacts joints No cure, anti-inflammatory drugs, steroids, immunosuppressants, pain relief
51
Natural active immunity
Body creates memory cells so that when pathogen is reencountered pathogen is immediately destroyed
52
Natural passive immunity
Antibodies cross the placenta into the baby while in the uterus - has some immunity at birth Colostrum (first milk produced) is very high in antibodies - gives breast fed baby the same level of immunity as the mother
53
Artificial passive immunity
Antibodies are extracted from one individual and injected into another
54
Artificial active immunity
Safe form of an antigen is injected (vaccine) into bloodstream, not the normal live pathogen
55
What may a vaccine contain
Killed or inactive bacteria/virus Weakened strains of a virus Altered (detoxified) toxin molecule Isolated antigens Genetically engineered antigens
56
How does a vaccine work
Form of safe antigen is injected into blood Primary immune response is triggered, body produces antibodies and memory cells If pathogen is encountered, secondary immune response is triggered and pathogen is destroyed rapidly
57
Contrast epidemic and pandemic
Epidemic - Communicable disease that spreads rapidly to a lot of people at a local or national level Pandemic - Disease spreads rapidly across a number of countries or continents
58
What is penicillin
Safe antibiotic, discovered by Alexander Fleming, from Penicillium mould
59
What is pharacogenetics
Interweaving knowledge of drug actions with personal genetic material Deciding treatment plan based on genetics
60
What is synthetic biology
Genetically engineering populations of bacteria to produce bacteria, that would otherwise be too rare, and expensive
61
What is selective toxixity
Antibiotics interfering with metabolism of bacteria and human cells
62
Why are antibiotics becoming less effective
Antibiotic resistance (random mutation of bacteria that is not impacted by the antibiotic, these reproduce and pass on mutation, creating a large population of antibiotic resistant bacteria
63
What does MRSA stand for, what is it
Methicillin-resistant Staphylococcus aureus common in hospitals Potentially fatal Was treated with methicillin but is not resistant
64
How can antibiotic resistance be reduced
Minimising use of antibiotics Complete each course of antibiotics Good hygiene

BIOLOGY OCR A (25 decks)

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