Communicable diseases Year 10 Flashcards
What are communicable diseases?
diseases that can be passed from one individual to another. these are caused by pathogens
What are pathogens?
microorganisims that cause disease
viruses, bacteria, protists or fungi
How do pathogens cause people to feel ill?
- cause damage to tissues = we feel ill
- bacteria may make** toxins** that damage tissues
- bacteria and viruses may spread rapidly throughout the body
How are communicable diseases spread?
- direct contact - touching an infected person (both sexual and non sexual)
- water - pathogens entering water supply, drinking contaminated watter or food it is added to
- air - when infected person sneezes or coughs tiny droplets spray out. another person breathes them in or lands on surfaces that other people touch
How do you reduce the spread of disease?
- contact - disinfecting surfaces, regular hand washing, avoided risky sexual contact, isolating sick idividuals
- water and food - sterilisation of drinking water using chemicals or UV light, cooking food, boiling water, treatment & safe disposal of sewage
- air - using a tissue when sneezing or coughing/ good ventilation
- all - vaccination for a specific disease so that people cannot pass it on
How do viral diseases work?
- viruses have genetic material enclosed in a protein coat
- reproduces using host cells they infect and enter
- viral genetic material used by host cell to replicate virus
- causes damage and death of cells as new viruses burst from infected cells
Examples of viral diseases
- HIV
- measles
- tobacco mosaic virus
what are the symptoms of HIV and how would it develop if left untreated?
- flu like illness
- early and ongoing treatment with antiretroviral drugs keeps virus under control
- untreated = leads to AIDS
- immune system is damaged so badly that it can not defend against other infections or cancer cells
How is HIV spread?
- sexual contact
- exchange of body fluids (eg blood)
What are the symptoms of measles?
- fever
- red skin rash
- can kill or cause pernament damage
- young children are vaccinated against it
How is mealses spread?
- in droplets when an infected person coughs or sneezes
What are the symptoms of tobacco mosaic virus?
- yellow patches in a “mosaic” pattern on leaves
- reduces photosynthesis & growth of plant
What are the symptoms of gonorrhoea?
- think green or yellow discharge from vagina or penis
- pain when urinating
How is gonorrhoea spread and treated?
- sexually transmitted
- treated with penicillin
- antibiotic resistant strands appeared = more people with disease
What are the symptoms of salmonella and what is it caused by?
- fever
- abdominal cramps
- vomiting
- diarrhoea
- bacteria invading tissues and secreting damaging toxins
How is salmonella spread?
- when bacteria is in food that is eaten
- source of contamination = infected animal or person’s faeces
- more likely when food is prepared in an unhygenic way
What kind of disease is rose black spot?
fungal disease
What are the symptoms for rose black spot?
- leaves develop purple or black spots
- leaves turn yellow and drop off early
- less healthy leaf tissue = growth of plant is slowed
how can rose black spot be treated?
- with fungicides- chemicals that specifically kill fungi (sprayed onto the leaves)
- removing and destroying the affected leaves
how do fungi reproduce?
- using microscopic spores
- small enough to be carried on the wind
What is malaria caused by?
- protist called plasmodium
How is malaria spread?
- starts in first host mosquito
- bites first person, they get infected
- second mosquito bites infected person and becomes a vector for the disease
- second (now infected) mosquito bites second person and passes on the disease
What are the symptoms of malaria?
- episodes of fever
- headache & high temperature
- could be fatal
How is the spread of malaria controlled?
- preventing mosquitos from breeding by draining water from ditches and small ponds
- using insecticides to kill the larvae
- using mosquito nets to prevent people being bitten while asleep
What are the four non specific human defence systems?
- skin
- trachea and bronchi
- stomach
- nose
How does skin act as a non specific defence system?
- physical barrier that pathogens cannot pass through
- glands in skin secretes substances that have antimicrobial properties (kill or stops the growth of pathogens)
How does the stomach act as a non specific human defence system?
- cells of stomach produces hydrochloric acid
- kills pathogens in food
How does the trachea and bronchi act as a non specfic human defence system?
- cells produce sticky mucus
- traps pathogens in inhaled air
- cilia (hair like projections) in bronchi move backwards and forwards)
- sweeps the mucus and pathogens to the throat to be swallowed
- pathogens die in stomach
How does the nose act as a non specific human defence system?
- nose hairs trap pathogens that are suspended in the air or attached to dust particles
- reduces the risk of infection of the lungs and throat
What are antibiotics for?
- kill bacteria
- do not kill viruses
- different types are needed to treat specific bacterial diseases
- new strains of bacteria that are resistant to antibiotics
- race to develop new types of antibiotics to kill resistant strains as they develop
What are painkillers for?
- treating the symptoms of the disease
- does not kill the pathogens
- will not cure the disease
Where does digitalis originate from?
foxgloves, used to treat heart conditions
Where did penicillin originate from?
- discovered by alexander fleming
- from the mould penicillium
- fungus contaminated a plate of agar which killed the bacteria that he was culturing
Where did aspirin originate from?
- extracted from willow tree
what are the three stages of drug testing?
- preclinical testing
- early clinical testing
- further clinical testing
What happens during preclinical testing?
- tests on cells, tissues, and live animals
- tests for toxicity, efficacy and dose
- takes place in a laboratory
What happens during early clinical testing?
- carried out on healthy volunteers
- tests for safety and toxicity
- uses very low concentrations of the drug
What happens during further clinical testing?
- carried out on patients with the disease
- tests for optimum dosage and efficacy
- includes double blind trials in which some patients are given a placebo
What is a double blind trial?
- both doctors don’t know which is the new drug or placebo to remove bias
