Biology - B3

Viruses - 1/100th the size of a bacturium - reproduce rapidly - replicate using cells which make them burst - cell damage = illness

Protists - single-celled eukaryoutes - some protists are parasites which live on organsiams and cause damage - vector

Bacteria - very small cells which can reproduce rapidly (1/100th of the size of body cells) - they produce toxins which damage cells

Funi - some are single-celled - others have a body made up f hyphae - grow and penetrate human skin and surface of plants

WATER - drinking or bathng in dirty water - cholera-bacterial infection

AIR - carried in the air and breathed in - airborne pathogens - cough and sneeze - influenza virus

DIRECT CONTACT - touching contaminated surfaces - skin - athletes' foot

Measles - spread by droplets from a sneeze or cough - red skin rash and a fever - can ead to pneumonia or encephalitis (brain infection) - most people are vaccinated

HIV - virus spread by sexual contact or bodily fluids - flu-like symptoms - attacks immune cells - if immune system is damaged, it can't cope with infections or cancer - AIDs

Tobacco mosaic virus (TMV) - affects plants (tomatoes) - mosaic patterns on leaves - discoloured leaves - can't carry out photosynthesis well

Rose black spot - a fungus that causes purple or black spots - the leaves can turn yellow and drop off - meaning photosynthesis can't happen - spreads in water or by the wind - treated by fungicides and by ********* the plants of its affected leaves and destroying them

Malaria - caused by a protist - inside a mosquito (vector) - mosquito feeds on another animal and infects it - causes repeating episodes of fever - can be fatal - can be reduced by stopping the mosquitos from breeding - people can be protected - insectiides and mosquito nets

Salmonella - bacteria that causes food poisoning - fever, stomach cramp, vomiting, diarrhoea - symptoms are caused by toxins - from food that has been containated - prepared in unhygenic conditions - UK poultry vaccination

Gonorrhoea - STD (sexual contact) - pain during urination, think yello or green discharge - originally treated with penicillin - some bacteria are resistant - spread-barrier methods - condoms

1. Being hygenic - washing hands

2. Destroying vectors - killing insects , destroying vectors

3. Isolating infected individuals - prevents passing on

4. Vaccination - can't develop infection and pass it on

Body - skin = barrier, hairs and mucus in the nose = trap, trachea + bronchi = mucus + cilia, stomach = hydrochloris acid

Immune system - three lines of attack 

1. White blood cells engulf foreign cells and digest them (phagocytosis)
2. They produce antibodies to fight against the unique antigens of the pathogen                              3. They produce antitoxins to couteract toxins from the invading bacteria  

- Vaccinations inolve injecting small amount of dead or inactive pathogens - these carry antigens which cause the body to produce antibodies to attac them

- If the pathogen returns, the white blood cells will remember how to produce the antibodies

PROS                                                                                                                                                  -  Vaccinnes have helped to cotrol lots of communicable diseases (small pox)                                  -  epidemics can be prevented

CONS                                                                                                                                                  -  they don't always work                                                                                                                      - bad reactions (rare)
    

Painkillers - relieve pain - but don't tackle the cause of disease - just reduce symptoms

Antibiotics - actually kill bacteria - different antibiotics kill different types of bacteria

Antibiotics don't destroy viruses - they use body cells - difficult to kill viruses and not the actual cells

Bacteria can mutate and become resistant to antibiotics - these will survive and reproduce - to slow it down - don't over-prescribe

- Plants produce chemicals to defend themselves against pests and pathogens

- Asprin - painkiller - from willow

- Digitalis - heart conditions - from foxgloves

- Microorganisms -  Alexander Fleming - mould - penicillin

1. Preclinical testing - human cells and tissues in the lab - blood pressure = a whole organism

2. Test on live animals - testing efficacy, its toxicity and the best dosage

3. Human volunteers in a clinical trial - drug tested on healthy volunteers (side effects) - low to high dose - then on unhealthy volunteers - optimum dose found - put in two group - one has drug - other has placebo - so doctor can see difference - blind testing - neither know what drug - peer review - false claims