Biology Infection and response (Pathogens (Can enter the body by (being…
Biology Infection and response
Microbes (micro organisms)
Can cause diseases
Can enter the body by
being breathed through the mouth or nose
being ingested in water or food
Enter through cuts or bites in the skin
other natural openings
The types are...
Bacteria - small living cells that produce toxins and reproduce very quickly
Fungi - produce spots and penetrate human skin
A virus - lives and reproduces quickly inside human cells, causing cell damage
Protists - eukaryotic cells that can spread through vectors
Our defence against microbes...
Hairs and mucus in the nose trap particles that may contain pathogens
The skin acts as a waterproof barrier
The breathing organs have hairs and produce mucus to cover the lining of these organs and trap pathogens
The stomach contains hydrochloric acid which kills bacteria
White blood cells
They eat the microbe
They produce antibodies to neutralise the microbe
They produce antitoxins to neutralise the poisons produced by microbes
Step 1: The white blood cell recognises the pathogen
2: The cell produces antibodies to "fit" the pathogen
3: The antibodies fit onto the pathogens and cause them to "clump"
4: The pathogens are engulfed by the white blood cells
Vaccinations work by injecting a small quantity of dead or inactive pathogen into the body. The body is tricked into producing antibodies ready for the real thing. The memory cells are then there to fight the real pathogen.
drugs used to relieve the symptoms of disease but without killing the pathogens e.g
The three stages of drugs being approved
Is it toxic? Preclinical tests are done on cells
Is it safe for animals? Animal tests are carried out
Is it safe for humans? Human volunteers are tested on. This begins with low doses
Clinical trials can be done in different ways
Blind trials - patients do not know which drugs they are taking - a real drug or a "placebo"
Double blind trial - Neither the doctors or the patients know if they're taking the real drug