B5: Communicable Diseases Flashcards
What is a Communicable Disease?
A disease caused by pathogens, which can be spread from one person to another.
What is a pathogen?
A microorganism which causes a communicable (infectious) disease, examples include bacteria and viruses.
Define health.
A state of physical and mental wellbeing.
What can cause diseases?
Pathogens (like viruses and bacteria) - communicable
Life situations (stress, poor diet, financial status, gender, where you live) - Non-communicable
What is a defective immune system?
An immune system which is not able to fight off viruses or other pathogens effectively (e.g. people with HIV)
What other diseases can physical diseases trigger?
Mental diseases (e.g. a person with arthritis cannot move, and thus develop depression due to the inability to lead a normal life)
How do bacteria cause harm to the body?
(Once in the body they multiply and, under the right conditions, can divide every 20 mins)
They release toxins which can damage tissues and make us feel ill.
How do viruses cause harm to the body?
Viruses can only reproduce inside a host cell - this can damage the cell because when the virus wants to leave the cell, the cell will burst open and die
How can pathogens be spread?
Air droplets (influenza)
Water (cholera)
Physical contact (HIV)
How can the spread of pathogens be reduced?
Practicing basic hygiene (e.g. washing your hands before eating)
Providing clean drinking water
Use sanitation (e.g. condoms during sex)
Isolating infected patients
Vaccination
Name 2 viral diseases
Measles and HIV (human immunodeficiency virus)
Why are viruses more dangerous that bacteria?
Viruses cannot be killed by antibiotics
(They multiply inside the cell, thus they are are harder to reach without damaging healthy cells)
What are the symptoms of measles?
Initial fever
A red skin rash after ~ 3 days
How is measles spread?
Air droplets from an infected person.
What are the dangers of measles?
Damage to the brain and breathing system.
- In severe cases can be fatal
How is measles treated?
Vaccination from a young age.
What are the symptoms of HIV?
Flu
How is HIV spread?
Physical contact (sex or sharing needles)
What are the dangers of HIV?
The symptoms are mild, therefore the patient is unable to tell when the virus is attacking the immune system and, over time, it becomes severely damaged
(At one point it becomes so badly damaged that it cannot fight off other diseases (e.g cancer)(defective immune system)
The patient is now more likely to develop cancer and TB (late stage HIV/ AIDS - fatal)
How is HIV treated?
Antiretroviral drugs (stop the virus from multiplying - patient does not develop AIDS)
What is a problem of treating HIV?
The patient has to take antiretroviral drugs for the rest of their life.
Name 2 bacterial diseases
Gonorrhoea and Salmonella
How is salmonella spread?
By ingesting infected food
- prepared in unhygienic conditions
What are the symptoms of salmonella?
Fever, abdominal cramps, vomiting and diarrhoea
(caused by toxins released from the bacterium)
Where is salmonella found?
Poultry - chickens
How is salmonella treated/prevented?
Vaccination
Antibiotics
Practicing hygiene when preparing food
How is gonorrhoea spread?
Physical contact - it is a sexually transmitted disease
What are the symptoms of gonorrhoea?
Thick yellow/green discharge from sexual organs
Pain when urinating
How can gonorrhoea be treated/prevented?
Antibiotic (penicillin, formerly. resistant strains of the bacterium are now common so it’s not used anymore)
Condoms
Isolating infected individuals
What is a vector?
An insect/ organism which carries a pathogen, but are not directly infected by it.
Name a protist disease
Malaria
(communicable, but cannot be passed from person to person, only through vector)
What are the symptoms of malaria?
Repeated bouts of fever - malaria can be fatal
How is malaria spread?
Through a vector (mosquito)
- The mosquito bites an infected person, where the malaria pathogen passes to the mosquito
- It then bites another person and spreads the pathogen
How can malaria be prevented?
Prevent the vector from breeding (drain areas of still water to prevent mosquitos from breeding/ insecticides)
Use a mosquito net
Name a viral disease occurring in plants
Tobacco mosaic virus
What types of plants does TMV affect?
Tobacco and tomatoes
What are the symptoms of TMV?
Discoloration of the leaves
Distinct mosaic pattern on the leaf
Why is TMV harmful?
The virus destroys the cells in the leaf, meaning the plant is unable to photosynthesise
This reduces crop yields
How is TMV spread?
Physical contact from infected plants
Vectors
How can the spread of TMV be prevented?
Pesticides
Good field hygiene (TMV can remain infectious in soul for ~ 50 years)
Name a fungal infection occurring in plants
Rose black spot
What type of plant can rose black spot affect?
Rose bushes
What are the symptoms of rose black spot?
Black/ purple spots on the leaves - often turn yellow and drop off (thus no photosynthesis and no flowering)
How is rose black spot spread?
Air - wind
Spread over the plant after rain
Dormant spores reside in dead leaves and stems
What is a non-specific defence system?
A system whose job is to prevent pathogens from entering the human body
How can rose black spot be prevented?
Burning dead plant matter
Fungicides
Destroy infected leaves
What are the 4 main parts of the non-specific defence system?
Skin
Nose
Lungs
Stomach
How does the skin prevent pathogens from harming the body?
It forms a protective layer - outer layer consisting of dead cells - making it difficult for pathogens to penetrate
Contains sebum which kills bacteria
When penetrated, it scabs over
How does the nose protect from pathogens?
Hair + mucus - trap pathogens which try to enter the body
How do the lungs protect from pathogens?
Trachea and bronchi are covered with cilia (covered in mucus - trap pathogens)
They now waft the mucus upwards to the throat where it is swallowed into the stomach
How does the stomach protect from pathogens?
Contains hydrochloric acid - kills pathogens before they make their way into the digestive system
What is the immune system?
The system which destroys pathogens and the toxins they produce
Also protects against the same type of pathogen, in case is invades again in the future
What does the immune system involve?
White blood cells
How can WBCs protect against pathogens?
Phagocytosis - ingest and destroy pathogens using enzymes
Antibodies - protein molecules produced, each is specific to the type of disease and they can remain in the blood for a long time (we can be protected if we encounter the same pathogen again)
Antitoxins - chemicals which stick to toxin molecules and prevent them from damaging cells
What are 3 types of responses plant have against
attack(?)?
Physical response
Chemical response
Mechanical response
Other than pathogens, what else can plants be attacked by?
Insects
Herbivores (animals)
What is are some physical responses?
Cell wall - difficult for microorganisms to penetrate
Waxy cuticle layer on leaves - also difficult to penetrate
Layer of dead cells (bark) - difficult to penetrate
What are some chemical responses?
Antibacterial chemicals - kill bacteria
Poisons - deter herbivores
