Defending ourselves against infectious disease
- Created by: Freya Woolley
- Created on: 07-05-15 17:27
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- Defending ourselves against infectious disease
- Pathogens
- Micro-organisms that cause infectious diseases
- Viruses, Bacteria, Protoctists, Fungi
- Parasites that live in or on the body of a host and causes harm
- Reproduce rapidly 1 per 20mins - bacteria
- Invade and destroy host cells
- Secretion of toxins/ poisons
- Viruses
- Smaller than bacteria
- Make more viruses inside host cell- burst out
- DNA and protein coat
- Bacteria
- Smaller than plant and animal cells
- Cytoplasm, membrane, wall, genes in plasmids
- Need: nutrients, oxygen, warmth and water
- Body is ideal so multiply rapidly- binary fission
- Growing microbes
- Culture medium must contain: Carbs, mineral ions
- Aseptic techniques
- Heat glassware to 100c to sterilise
- Spread of disease
- Droplet infection: when you are ill you expel tiny droplets full of pathogens- sneezing
- Contam. food and drink: raw or undercook, unpure water- diarrhoea, salmonella
- Microbes go straight to the gut
- Break in skin: HIV/Aids can enter through cuts or scratches
- Direct contact: genital herpes spread by contact of skin
- Defence
- Barriers, phagocytes, specific immune responses
- Clotting forms scabs and stops pathogens entering
- Cilia & muscus line respiratory passages, pathogens stick to them
- Stomach produce HCL acid
- Phagocytes (wbc) engulf and ingest pathogens
- Lymphocytes produce antibodies for the anigens
- Vaccination
- Inject a modified toxin
- Injecting a modified live bacteria or virus
- Injecting dead bacteria or virus
- Injecting parts of antigens which act as antigens
- Bacterial Mutations
- A change in the DNA of an organism
- If mutated are resistant to antibiotics
- Antibiotics cannot kill viruses
- Natural selection- evolution, the fittest survive, breed and pass on the useful characteristic
- Pathogens
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