Transcript Microbes
11/04/2016 Microbes and Disease W Richards The Weald School Microbes 11/04/2016 Microbes are micro organisms that are too small to be seen. A pathogen is a microbe that can cause diseases if it enters the body: They can be breathed in through the mouth or nose …or other natural openings… They can be ingested (eaten) through the mouth They can enter through cuts or bites in the skin or just by touching something Microbes: our defence against them 11/04/2016 Our bodies have many defence mechanisms against invading microbes: The skin acts as a barrier Stomach produces stomach acid If our skin is cut platelets seal the wound by clotting Tears contain an enzyme that kills bacteria The breathing organs produce mucus to cover the lining of these organs and trap the microbes Disease 11/04/2016 A disease is any condition where the body isn’t working as it should. This could be caused by a malfunction in the body (as with diabetes), or it could be caused by the two types of MICROBE: Bacteria Viruses •1/1000th mm big •1/1,000,000th mm big •Living cells (some are harmless) •Genetic info inside a protein coat •Grow very quickly •Not affected by antibiotics •Affected by antibiotics •Release poisons •Examples: food poisoning, tetanus, sore throats •Examples: colds, flu, polio, chicken pox Fungi 11/04/2016 Fungi are another form of microbe. There are many different varieties ranging from bread mould to mushrooms. Fighting disease If microbes do enter our body they need to be neutralised or killed. This is done by WHITE BLOOD CELLS: White blood cells do 3 things: 1) They eat the microbe 2) They produce antibodies to neutralise the microbe 3) The produce antitoxins to neutralise the poisons produced by microbes 11/04/2016 Producing antibodies 11/04/2016 You’re going down Step 1: The white blood cell “sees” the antigen (microbe) Step 2: The cell produces antibodies to “fit” the antigen Step 3: The antibodies fit onto the antigens and cause them to “clump” Step 4: The antigens are “eaten” by the white blood cells Fighting disease NATURAL IMMUNITY This is when antibodies are produced by a person when needed or they are passed on by the mother during pregnancy. ARTIFICIAL IMMUNITY A vaccine with dead microbes is injected – the body is “tricked” into producing antibodies ready for the real thing. This is called PASSIVE IMMUNISATION 11/04/2016 Using Antibiotics 11/04/2016 Antibiotics can be used to kill bacteria. However, there are two problems: 1) Overuse of antibiotics can lead to bacteria becoming resistant 2) Antibiotics have no effect on a virus, like the common cold. A virus must be allowed to “run its course”.