Commincable Diseas - Module 4 Flashcards
What is a communicable disease and what causes it?
A communicable disease is an infectious/contagious disease caused by pathogens
What are the 4 types of pathogens?
- Bacteria
- Virus
- Fungi
- Protist
How do virus’ damage cell host?
Virus takes over the metabolism and the viral DNA is inserted into the host DNA - making more virus which will eventually burst out the cell destroying it
How do protists damage the host cell?
Protists digest the contents of the cell as they reproduce
How do bacteria damage host tissues?
Produce toxins that cause disease
What is ring rot? Which pathogen causes it?
Ring rot, bacterial disease, damages leaves, tubers and fruit of potatoes and tomatoes
What is TMV? What pathogen causes it?
Tobacco mosaic virus, TMV, a virus
Damages leaves, flowers and fruit as it stunts growth
What is potato blight? What pathogen causes it?
Potato blight, affecting tomatoes and potatoes, is caused by a fungus
The hyphae destroy leaves and tubers
What is black Sigatoka? What pathogen causes is?
Black Sigatoka is a fungal banana disease
The hyphae turns the leaves black, reducing yield of bananas
What is TB? And what pathogen causes it?
Tuberculosis (TB) is a bacterial disease
Damages lung tissues and suppresses immune system
Is TB preventable?
Yes - there is a vaccine
Is TB treatable?
Yes - there is antibiotics
What is bacterial meningitis? What pathogen causes it?
Bacterial meningitis is a bacterial infection of the membrane of the brain
Causes blood poisoning resulting in rapid death
What are the symptoms of bacterial meningitis?
Blotchy red rash that does not disappear when a glass is pressed on it
Is bacterial meningitis preventable?
Yes - there is a vaccine
Is bacterial meningitis curable?
Yes there are antibiotics
What is HIV/AIDS? And what pathogen causes it?
HIV is caused by a virus
It destroys the immune system leaving sufferers vulnerable to other diseases
Is HIV/AIDS preventable?
Safe practices; protected sex, don’t share needles, don’t contaminate blood
Is HIV/AIDS curable?
No - there is no vaccine but anti-retroviral drugs slow the progression of the disease
What is influenza? What pathogen causes it?
Influenza is a viral infection
It destroys ciliated epithelial cells leaving airways open to infection
What is malaria? What pathogen causes it?
Malaria is caused by the protoctist plasmodium
And it is transferred by mosquitoes (vector)
It invades blood cells, liver and brain and it makes people weak and vulnerable to other infections
Is malaria preventable?
There is no vaccine but to control malaria the vectors need to be controlled through mosquito nets, insectasides
What is ring worm? What pathogen causes it?
Ring worm is a fungal disease
Causes crusty infection areas of skin
How is ring worm cured?
Antifungal creams
What is athletes foot and which pathogen causes it?
Athletes foot is a fungal disease, a form of human ring worm
Causes itchy and sore areas between he toes
How is athletes foot cured?
Antifungal creams
What is direct transmission?
When a pathogen is transferred directly from one individual to another
Describe the 3 ways of direct transmission
- Direct contact
Kissing, exchange of bodily fluids, skin to skin contact - Inoculation
Break in the skin, animal bite, puncture wound (sharing needles) - Ingestion
Contaminated food or drink
What is indirect transmission?
Where a pathogen travels between individuals indirectly
Describe the 3 ways of indirect transmission
- Fomites
Bedding, socks, cosmetics being shared - Droplet infection (inhalation)
Coughing, sneezing particles then being breathed in - Vectors
Something that transmits communicable disease (mosquitoes)
Can communicable disease be passed between human and animals?
YES - bird flu
What factors affect the probability of catching communicable disease?
- Overcrowded living conditions
- Poor nutrition
- Compromised immune system
- Infrastructure
- Socioeconomic factors (lack of trained healthcare workers)
What is direct transmission in plants?
Direct contact of a healthy plant with any part of a diseased plant
Describe the two ways of indirect transmission in plants?
- Soil contamination
Infected plants leave pathogens or spores in soil infecting next crop to be planted there - Vectors
Wind carrying spores, water, animals, humans
What factors affect the chances of plants being infected with communicable disease?
- Planting crops susceptible to disease
- Over crowding
- Poor mineral and nutrition
- Damp and warm conditions (increase survival and spread of pathogens)
Why do plants not heal diseased tissues?
They are continually growing and meristems can replace damaged parts
What is Callose and what does it do?
Callose is a polysaccharide that is deposited between cell wall and cell membrane, plasmodesmata and phloem to stop pathogen entering cells around infection site
How do plants respond to pathogens?
Plants respond rapidly through receptors stimulating release of signalling molecules triggering a response
Name and describe some of the chemical defences used by plants
- Insect repellants such as pine resin and citronella
- Antibacterial compounds such as phenols
- Antifungals such as chitinases enzymes which break down chitin cell wall of fungi
- Anti-oomycetes such as glutamates that break down polymers in cell walls of oomyceters
List the main 3 barriers keeping pathogens out of the body
- Skin
- Body tracts are lined with mucous membranes trapping microorganisms
- Lysosomes and stomach acid
What are expulsion reflexes and what do they do?
Coughs and sneezes, vomiting and diarrhoea
All expel pathogens from gas exchange system/gut
What is the role of thromboplastin?
An enzyme that triggers the formation of a blood clot
What is the role of serotonin?
Makes smooth muscle in blood vessels contract so they reduce blood flow to damaged area
How is inflammation characterised?
Pain, heat, swelling and redness
When damaged tissues activate mast cells, what do they do?
Release histamines and cytokine chemicals
What is the role of histamines? [2]
Cause blood vessel dilate causing redness and heat stopping pathogen reproducing due to temperature
Make blood vessel walls leaky so plasma is forced out as tissue fluid causing swelling and pain
What is the role of cytokines?
Attracts phagocytes to the area to dispose of pathogens
How do fevers get rid of pathogens?
Cytokines stimulate hypothalamus to increase bodily temperature so pathogen can’t reproduce and specific immune system works faster at a higher temperature
What do phagocytes do?
Engulf and destroy pathogens
What are the two type of phagocyte?
- Neutrophil (multi-lobed nucleus)
- Macrophage (round nuclei)
Describe to stages of phagocytosis
- Pathogens produce chemical attracting phagocytes
- Phagocytes recognise pathogen as non-self
- Phagocyte engulfs pathogen - phagosome
- Phagosome and lysosome combine - phagolysosome
- Digestive enzyme in lysosome digests pathogen
What does a macrophage do following the normal process of phagocytosis?
It combines antigens from pathogen surface with glycoproteins in cytoplasm - forming the MHC (major histocompatibility complex)
MHC moves pathogen antigens to macorphages cell surface membrane - so it becomes an antigen presenting cell
What is the role of the antigen presenting cell?
Stimulate cells involved in specific immune system response
What are opsonins?
Type of antibody that bind to pathogens and tag them so they are more easily recognisable by phagocytes
What are immunoglobulins?
Antibodies - Y shaped glycoproteins
What do antibodies do?
Bind to specific antigens on pathogens or toxins triggered by immune response
Describe the structure of an antibody
- Two long identical polypeptide chains - heavy chains
- Two shorter identical chains - light chains, form the variable region
- 2x antigen blinding sites
- Receptor binding site at bottom of heavy chains
- Hinge region to allow flexibility
Why is hinge region on an antibody useful?
Allows the two binding sites to bind to two different antigens
What holds the chains together in the structure of an antibody?
Disulphide bridges
How do antibodies act as agglutinins?
Cause pathogens with antigen - antibody complexes to clump together
What is formed when antibody binds to an antigen?
Antigen - antibody complex
How do antibodies act as anti - toxins?
By binding to toxins, antigens make toxins harmless
How does the antigen - antibody complex get engulfed by phagocyte easily?
Acts as an opsonin, signalling phagocytes to come to thee area
Where do B lymphocytes mature?
In the bone marrow
Where do T lymphocytes mature?
In the thymus gland
What are lymphocytes?
White blood cells used in the specific immune system
What are the 4 types of T lymphocytes?
T HELPER
T KILLER
T MEMORY
T REGULATOR
What do T killer cells do?
Release perforin making membrane freely permeable
What do T memory cells do?
Are a part of the immunological memory - if they meet an antigen a second time they ill divide rapidly into clones of T killer cells
What are T regulator cells?
Suppress immune system to control it once a pathogen has been eliminated
Why are T regulator cells so important?
So than an autoimmune system is not set up
What do T helper cells do?
Using CD4 receptors on cell surface membranes, the bind to antigens on antigen presenting cells and produce interleukins to stimulate activity of B cells
What are interleukins?
Type of cytokines that cell signal
What are the 3 types of B lymphocytes?
- Plasma cells
- B effector cells
- B memory cells
What do plasma cells do?
Produce and release particular antibodies
What do B effector cells do?
Divide to form plasma cell clones
What do B memory cells do?
Programmed to remember antigens and enable rapid response if reinfected
Describe cell mediated immunity
- Macrophages become antigen presenting cells in the non specific defence system
- Receptors on T helper cells fit antigens and produce interleukins making more T cells, som becoming T helper that fit pathogen
- Cloned T cells may develop into; T memory cells, T killer cells, produce interleukins to stimulate phagocytosis or B cell division
What does cell mediated immunity respond to?
Cells that have been changes; virus infection, mutation
What does humoral immunity respond to?
Antigens found outside of cells like bacteria, fungi and antigen presenting cells
Describe humoral immunity
- B cell with antibodies will bind and engulf to antigens on pathogen and become an APC
- Clonal expansion occurs - Activated T helper cell bind to B effector cell APC and interleukins (produced by T helper cell) activate B cell to divide and give clones of plasma cells and b memory cells
- Plasma cells produce antibodies - this is the primary response and may take a while to come into effect
- B cells develop into memory cells which will create the secondary immune response
What is an auto immune disease?
When the body starts attacking health body tissue
What are 3 common autoimmune diseases?
- Type 1 diabetes
- Rheumatoid arthritis
- Lupus
What are non communicable diseases?
Diseases that cannot be passed from one person to another
What are the two forms of natural immunity in the body?
- Natural active immunity e.g production of antibodies and memory cells
- Natural passive immunity e.g antibodies passed from a mother to baby through placenta or breast milk whilst it build its own immune system
What is artificial passive immunity?
Temporary immunity where antibodies are taken from one individual and injected into the blood stream on another for potential fatal diseases e.g rabies and tetanus
What is artificial active immunity?
When the immune system of the body is stimulated to make its own antibodies in the form of a vaccine
Describe how vaccination works
- Pathogen is made safe
Inactive/dead , weakened strai, genetically engineered antigens - Small amounts of safe antigens injected into blood
- Primary immune system responds - producing antibodies and memory cells
- If a live pathogen is come into contact with immune system has memory cells to rapidly get rid of pathogen
What is an epidemic?
Spread of communicable disease at a local or national level
What is a pandemic?
When the same disease rapidly spreads across a number of countries and continents
Describe some of the common medicines derived from living organisms
- Penicillin - antibiotic from mould
- Aspirin - painkiller from willow bark
- Digoxin - heart dug from foxgloves
What is pharmacogenetics?
Using knowledge of drug action with personal genetic material so that the treatment you receive is personal T you
What is synthetic biology?
Using genetic engineering to develop populations of drugs that would be rare, expensive or unavailable
What is selective toxicity?
The ability of antibiotics to interfere with metabolism of bacteria but not of humacells
