Biology B1 part 2

Infectious Disease
1. Pathogens
  1. They are micro-organisms that cause disease, there are 4 different types
  2. Protozoa (e.g. dysentery)
  3. Viruses (e.g. Flu)
  4. Bacteria (e.g. cholera)
  5. Fungi (e.g. athlete's foot)
2. Malaria
  1. It is caused by a protozoan, this protozoan is a parasite
  2. It is carried by mosquitoes, they are vectors
    1. Vectors can carry the disease without getting it themselves
  3. Preventing
    1. Mosquito nets
    2. Fish can be introduced to eat mosquito larvae
    3. Places that mosquito's go can be sprayed with insecticides
3. Immune system
  1. Once inside your body, pathogens reproduce rapidly
  2. White blood cells have the job of destroying them, they constantly patrol your body
  3. Lines of attack
    1. 1) Consuming - they engulf foreign cells and digest them
    2. 2) Producing antitoxins - they counter the effects of any poisons
    3. 3) Producing antibodies - each pathogen has unique molecules on the top, these are called antigens, when the white blood cells come across an antigen, they produce a specially designed antibody to kill it
      1. The antibodies are then produced rapidly and flow around the body to kill the rest off
      2. Some memory cells stick around so that if the person is infected again they can instantly kill it off
Preventing and treating
1. Antibiotics
  1. They are drugs that kill off bacteria without killing body cells
  2. They can't kill viruses
  3. Antivirals treat viral infections, they stop viruses from reproducing
  4. Some bacteria are naturally resistant to antibiotics (e.g. MRSA)
2. Immunisation
  1. Risks
    1. Can cause short term effects like...
      1. Swelling and redness at the injection site
      2. Feeling a bit under the weather
    2. You can't have vaccines if you are already ill because you immune system is weak
    3. People think that immunisation can cause other disorders (e.g. some people think there is a link between the MMR vaccine and autism
  2. Benifits
    1. Stops the disease from spreading easily
    2. It stops you from getting ill
  3. You can get very ill and even die from pathogens
    1. To avoid this, you can be immunised
      1. It involves injecting dead or inactive pathogens into the body
        Your white blood cells produce antibodies to attack them
        Some of these memory cells will stick around to kill off the disease if you get it
  4. Active immunity is where the immune system makes it's own antibodies after being stimulated by a pathogen
  5. Passive immunity is when antibodies are made by another organism, passive immunity is only temporary
Cancer
1. Tumors
  1. Benign - the tumour grows until it runs out of room, it stays in the same place, it isn't normally dangerous
  2. Malignant - the tumour grows and can spread to other parts of the body, they are very dangerous and can be fatal
  3. Reduce your risk
    1. Not smoking reduces your risk of getting lung cancer
    2. Eating less processed meat and more fibre can reduce the risk of colon cancer
2. Drugs
  1. New drugs must be tested before they are given to human
    1. 1) Computer models simulate the reaction of a human to the drug, promising one's go onto the next stage
      1. 2) The drugs are then tested on human tissues, again promising one's go onto the next stage
        3) The law states that new drugs must be tested on at least two different live mammals
        4) It is then tested on humans, this is called a clinical trial, in the trial, there are two groups of patients, one gets the new drug, the other get a placebo (it doesn't do anything) or the best existing treatment
Drugs
1. Beneficial and harmful
  1. Drugs change the way our bodies work, they can be very dangerous, this is why you can only get some drugs on perscription
  2. Some people get addicted to drugs and get withdrawal symptoms if they don't have it
  3. Tolerance develops with some drugs, this means you get used to having it and have to have a higher dose to get the same effect
  4. If someone is addicted, rehabilitation can help
2. Types
  1. Depressants (e.g. alcohol, temazepam
    1. They decrease the activity of the brain, causing slow reactions and poor judgement of speed and distance
  2. Stimulants (e.g. nicotine, caffeine)
    1. Opposite of depressants, they increase the activity of the brain, it is sometimes used to treat depression
  3. Painkillers (e.g. aspirin, paracetamol)
    1. They work by reducing the amount of painful stimuli at nerve endings
  4. Performance enhancers (e.g. anabolic steroids
    1. Sometimes taken by athletes, they help build muscle
  5. Hallucinogens (e.g. LSD)
    1. They distort what's seen and heard and heard by altering the pathways that the brain sends messages along
3. Illegal
  1. Categorised into three categories, class A is the most dangerous
    1. Class A - heroin, LSD, ecstasy, cocaine
      1. Class B - cannabis, amphetamines (speed)
        Class C - anabolic steroids and tranquillisers

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Biology B1 part 2

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	Created by Lara Coffin over 11 years ago