Please enable JavaScript.
Coggle requires JavaScript to display documents.
B5: Communicable diseases - Coggle Diagram
B5: Communicable diseases
Health and disease
Communicable diseases are caused by pathogens such as bacteria and viruses that are contagious. Non- communicable diseases cannot be transmitted. Both are major causes of ill health.
Factors that affect health:
Diet
Stress
Life situation
Health problems can interact with each other:
Viruses can cause cancer such as HPV which causes cervial cancer.
Mental health such as depression can be triggered if someone suffers from severe physical health problems.
Immune reactions in the body can be caused by a pathogen can sometimes trigger allergies
Pathogens
Microorganisms that cause disease are called pathogens. They are either caused direclty by the pathogen or a toxin released by it. Bacteria divide rapidly by splitting in two (binary fission). However, virsuses are not living things. They live inside cells and replicate themselves until the cells bursts, releasing the virus.The cell damage is what makes us feel illl.
How pathogens spread:
Air - Pathogens are carried in the air when someone infected breathes because they expel tiny droplets full of pathogens. Other people breathe in the droplets along with the pathogen so they pick it up.
Water- Pathogens can be picked up by drinking dirty water and fungal spores carried in splashes of water can spread plant diseases.
Contact- Pathogens can be picked up by touching contaminated surfaces.
Plant pathogens
Plants need mineral ions from the soil. If there aren't enough plants suffer deficiency problems:
Nitrates are needed to make proteins and therefore for growth. A lack of nitrates cause a stunted growth
Magnesium ions are needed for making chlorophyll, which is needed for photosynthesis. Plants without enough magnesium have yellow leaves which is known as chlorosis.
The common signs for plants that have diseases are:
stutedd growth, spots on leaves, decay, discolouration, malformed stems or leaves and visible pests.
They can be identified by:
Looking up the signs in a gardening manual or website
Taking the infected plant to a laboratory
Using test kits that identify the pathogen using monoclonal antibodies
Culturing bacteria practical
Nutrient broth solution, is a solution that contains all the needed nutrients for the bacteria to grow and survive.
Sterilise petri dish, nutrient broth and agar. Sterilise inncoulating loop by passing it through a bunsen burner flame.
Attach lid with tape, which stops unwanted organisms from entering place the petri dish upside down to stop the moisture from dripping down and disrupting the colonies.
Place in an incubator at 25C which reduces chances that harmful bacteria grow.
Diseases
Viral diseases
Measles:
A viral disease that is spread by droplets from an infected person's sneeze or cough. You get red skin rashes or signs of fever, it can lead to pneumonia or brain infecton. Most people are vaccinated against it.
HIV:
A virus spread through exchanging bodily fluids. There are flu-like symptoms and it can be controlled using antiretroviral drugs. This stops the replication. The virus attacks immune cells and if they become badly damage and can not cope with other infections it is then known as AIDS.
Tobacco Mosaic virus:
Affects plants. Causes mosaic patterns on the leaves and they become discoloured which means they can not carry out photosynthesis well so it affects growth.
Bacterial diseases
Salmonella:
A type of bacteria that causes food poisoning. You can suffer from fever, stomach cramps, vomiting and diarroea. It can be caused by eating undercooked food or prepared in unhygienic conditions. Poultry is vaccinated against it.
Gonorrhoea:
A sexually transmitted disease. Early symptoms include thick yellow or green discharge from the vagina or penis and pain when urinating. Originally treated with penicillin but it has become resistant. Antibitoic can be used.
Fungal and protist caused diseases
Rose black spot:
A fungus that causes purple or black spots on the leaves or roses. The leaves turn yellow and drop off. This means photosynthesis is limited. The gungus spreads through air and water. Gardeners treat the disease using fungicides and the flowers are burned so they do not spread.
Malaria:
Caused by a protist. Part of the malrial protist's life cycle takes part inside the mosquito. Malaria repeatedly causes fever. It is fatal. Damages the liver and red blood cells. People can be protected using nets and insecticides and antimalarial drugs.
Preventing bacteria
Antibiotics on bacterial growth
Clean the bench with disinfectant solution and sterilise innoculating loop through a bunsen burner flame.
Open a sterile agar plate gel near a bunsen burner so the flame kills bacteria in the air.
Use loop to spread bacteria over plate.
Place sterile filter paper discs containing antibiotic onto plate and incubate.
You can measure the radius to find area to see the effect the antibiotics had on the bacteria.
Antiseptic: Disinfectans that is safe to use on skin.
Antibiotic: Chemicals that can be used inside our bodies
Disinfectants: Chemicals used to kill bacteria in the environment.
Preventing infections
Being hygienic
Destroying vectors
Isolating
Vaccination
Human defence response
Skin- Acts as a barrier to pathogens. Also secretes antimicrobial substances which kill pathogens.
Hair and mucis in nose traps particles containing pathogens.
Trachea and bronchi secrete mucus and are lined with cilia which waft the mucus up to the back of the throat where it can be swollowed.
Stomach produces hydrochloric acid which kills microorganisms you swallow.
White blood cells -Consume the foreign cells and digest them in a process called phagocytis Invading pathogens have unique molecules called antigens on their surfaces. Or when a white blood cells comes across a foreign antigen they will produce proteins called antibodies to lock on to the invading cells so it can be found and destoryed by other white blood cells. The antibodies produced are specific to that type of antigen. They are produced rapidly and if the same pathogen infects the person again the white blood cells will produce the antibodies to kill it.
Plant defence response
Physical barriers:
Cell walls made from cellulose surround plant cells in case pathogens make it past waxy cuticle on leaves and stems.
They have layers of dead cells around their stems that act as a barrier.
Chemical barriers:
Produce antibacterial chemicals which kill bacteria and other plants produce poisns which deter herbivores
Mechanical defences:
Plants have thorns and hairs which deter animals from eating them.
Leaves may drop or curl if something touches them so that insects are knocked off.
Mimicry: Plants droop to mimic unhealthy plants or mimic butterfly eggs on their surfaces so real butterflies do not lay their eggs there.