infection and response Flashcards
What are pathogens? What are the four examples of them?
Pathogens are microorganisms that cause an infectious disease. This is only for communicable disease. The examples are protists, viruses, bacteria and fungi.
What is the size of bacteria? How do they cause disease?
Bacteria are very small, about 1/100th of body cells. Once they are inside the body, they reproduce rapidly, up to every 20 minutes. They can then produce poisons or toxins that damage tissues to make us feel ill.
What is the size of viruses? How do they cause disease?
Viruses aren’t cells, they are 1/100th of bacteria cells. They only reproduce inside a host cell. When they invade a host cell, they reproduce using its DNA, which damages the cell so that it bursts and dies.
How do protists cause disease?
Protists are single celled eukaryotes or parasites which live on or in other organisms. They are usually transmitted by a vector, which itself doesn’t get the disease.
How do fungi cause disease?
Fungi are single celled or have a body made of hyphae which can grow and penetrate human skin or the surface of plants. They produce spores, which spread from plants and animals.
How do you reduce the spread of disease?
reducing spread of disease:
- washing hands and being hygienic
- clean drinking water
- using a condom
- isolate infected individuals
- destroy vectors
- vaccination
What type of disease is measles? Describe the symptoms, the effects and how it is spread.
measles:
- a virus
- symptoms are fever after 3 days, red rash
- spread in droplets when infected person coughs or sneezes
- can damage breathing system and brain
- children vaccinated
What type of disease is HIV? Describe the symptoms, how it happens, how it is spread and how to stop it (temporarily).
HIV:
- a virus
- initially it is a flu-like illness, but disappears after a few weeks
- virus attack immune system which becomes severely damaged until it can’t fight off other infections that are usually easily dealt with or it can’t cope with cancer cells
- spread by sexual contact or exchanging bodily fluids
- antiretroviral drugs stop early stage HIV so the immune system is not damaged. this is not a cure, so this must be taken for their entire life
What type of disease is rose black spot? Describe how it is spread, the symptoms and how it is treated.
rose black spot:
- fungal disease
- causes leaves to develop purple and black spots
- leaves then turn yellow and drop off
- spread by water or wind
- treat by spraying plant with fungicides (chemicals that kill fungi) or remove infected leaves and destroy them
What type of disease is gonorrhoea? Describe the symptoms, how was it originally treated and how you prevent the spread of it.
gonorrhoea:
- bacterial disease
- sexually transmitted disease
- symptoms are thick yellow or green discharge from the penis or vagina, and pain when urinating
- originally treated with antibiotic penicillin, but now some bacteria are resistant to this
- prevent spread with condom and new antibiotics
What type of disease is tobacco mosaic virus? Describe the symptoms and the treatment.
tobacco mosaic virus:
- viral disease
- widespread plant pathogen that infects tomatoes etc.
- causes discolour on leaves in mosaic pattern
- affects growth as rate of photosynthesis is decreased
- treatment is removing all infected plants
What type of disease is malaria? Describe the symptoms, how it is spread and how to prevent the spread of it.
malaria:
- protist disease
- symptoms are repeating episodes of fever which can be fatal
- infected person is bitten by mosquito, the malaria pathogen passes into the mosquito, which is now the vector. this mosquito multiplies and bites others to pass on the malaria pathogen
- prevent by stopping vector from breeding (they breed in still water, so drain these areas or spray with insecticide which kills mosquitoes)
- prevent from biting, so use mosquito net and spraying net with insecticide
What type of disease is salmonella? Describe how it is spread, the symptoms and how to prevent it.
salmonella:
- bacterial disease
- spread by ingesting infected food, prepared in unhygienic conditions
- symptoms are fever, abdominal cramps, vomiting and diarrhoea caused by the toxins secreted
- chicken are vaccinated against salmonella
What are the four non-specific defense systems in the body to prevent pathogens from entering the body?
non-specific defense systems:
1) skin
- outer layer is dead cells, difficult for pathogens to penetrate
- produces sebum which kills bacteria
- scabs stop pathogens from entering the bloodstream
2) nose
- hair and mucas to trap pathogens
3) trachea and bronchi
- covered with cilia (hairs) which are covered in mucas, and they waft it to the throat where it’s swallowed into the stomach
4) stomach
- contains hydrochloric acid which kills pathogens before they enter the digestive system
Describe the process of phagocytosis.
phagocytosis:
- white blood cells ingest and destroy pathogens
- they detect the chemicals released from a pathogen, move towards it, ingest it and use enzymes to destroy it
Describe the process of antibody production.
antibody production:
- antibodies are protein molecules produced by white blood cells
- every pathogen has unique molecules called antigens on its surface
- white blood cells produce antibodies specific to the antigen
- when the antibody meets the antigen, it triggers them to be destroyed
- the antibody is now rapidly produced and carried around the body
- they remain in the blood for a long time, so we are naturally immune
