B6 Preventing and Treating Disease

• 1. The vaccine's dead / inactive pathogens enter the body and are recognised as an invader by the white blood cells.
  2. White blood cells produce antibodies to attack the pathogen
  3. These antibodies in the blood then cause special white blood cells called memory cells to be made.
  4. If the real pathogen then enters, the memory cells produce antibodies much quicker to attack and destroy it.
  5. The pathogen now cannot reproduce and is destroyed quickly.
  6. The body is now immune to that pathogen.
• A vaccine contains small amounts of dead or inactive pathogens, which are put into the body. When they enter, the white blood cells recognise that they aren't good for the body by their antigen. Then, the white blood cell creates antibodies, which then attach to the antigen of the pathogen. This means the pathogen is now destroyed.

  After that, the antibodies cause memory white blood cells to be made, which remember the antibody. This means if the pathogen enters again the antibodies are made much quicker and the pathogen gets destroyed by the phagocytes pathogen before the person gets ill.
• An antigen is the recogntition molecule. It is a different shape on different pathogens.
• An antibody is made by white blood cells. They join to the antigens on pathogens to destroy them.
• A vaccine contains dead or inactive pathogens to train the immune system.
• A White Blood Cell is one of your cells which kills pathogens.
• A Memory Cell is what a white blood cell turns into so that it can remember pathogens and make the same antibodies again.
• A Pathogen is any microorganism which causes disease.
• Herd Immunity is when some people are vulnerable but cannot get vaccinated but will have immunity as the disease can't get to them due to most people being vaccinated, which destroys the disease.
• Painkillers (such as Aspirin) are drugs that relieve pain but they don't tackle the cause of the disease or kill pathogens. They just reduce the symptoms.
• Antibiotics (such as Penicillin) actually kill the bacteria causing the problem without kill your own body cells.
• Antibiotics don't destroy viruses as viruses reproduce using your body cells, which makes it hard to develop drugs that only kill the virus and not the body cells.
• 1. Bacteria can mutate - sometimes the mutations cause them to be resistant to an antibiotic.
  2. If you have an infection, some of the bacteria might be resistant to antibiotics.
  3. This means that when you treat the infection, only the non-resistant strains of bacteria will be killed.
  4. The Individual resistant bacteria will survive and reproduce, and the population of the resistant strain will increase but will not be able to be destroyed by antibiotics.
• Antibiotics will not be given out for small illnesses such as a sore throat because Doctors must slow down the rate of development of resistant strains.
• With Antibiotics, you must finish the whole course and not stop when you feel better because you would have only killed the least resistant bacteria and that will give the most resistant bacteria more space to reproduce.
• Some chemicals released by plants are used as current medicines for humans. Such as, Aspirin is used as a pain killer and it was developed from willow. Digitalis is used to treat heart conditions and it was developed from foxgloves.
• Some drugs were extracted from microorganisms. For example, Alexander Fleming discovered penicillin from a mould on his petri dish as the area around the mould was free of bacteria. This was because the mould was producing a substance that killed bacteria.
• When developing drugs there are 4 important factors to consider:

  • Safe (No unwanted harmful chemicals)
  • Effective (Good at treating the disease)
  • Uptake and Removal (The body absorbs the drug, and clears it when it's used)
  • Stable (Can be stored for a long period of time and used in normal conditions)
• The Stages of Drug Discovery:

  
  

  • Testing on cells and tissues to test if it damages them (toxicity)
  • Testing on animals to test whether it is harmful to the whole body. Usually, it is done with rats (toxicity)
  • Testing on healthy volunteers, which tests for side effects.
  • Testing on a small number of patients, which tests the effectiveness of the drug and the dosage needed
  • Bigger Clinical Trials to test effectiveness and dosage on a bigger scale.
• The Clinical Trials are a double blind trial meaning that the patient in the study doesn't know if they are getting the drug or the placebo. The Doctor also doesn't know which one he is giving out. This can often cause the placebo effect.
• The placebo effect is when you make some feel better even though they haven't received treatment.
• A placebo is a fake drug.
• The Process of making Monoclonal Antibodies:

  1. A specific pathogen is injected into a mouse
  2. The mouse naturally produces B Lymphocytes, which produce antibodies specific to the antigen.
  3. The B Lymphocytes are removed from the mouse.
  4. These are then combined with tumour cells as tumour cells divide quickly. These are called Hybridoma Cells.
  5. The Hybridoma Cells copy themselves and produce millions of monoclonal antibodies specific to the original antigen.
• Monoclonal Antibodies can trigger the immune system by making cancer cells more noticeable.
• Monoclonal Antibodies may bind to receptors on cancer cells, removing the stimulus to grow and divide. They may also carry drugs or radioactive therapies to cancer cells.
• Monoclonal antibodies are used in pregnancy tests because the hormone HCG is only found when they are pregnant.

  If you are pregnant:

  • The hormone will bind to the antibodies on the blue beads.
  • The urine moves up the stick, carrying the hormone and the beads.
  • The beads and hormones bind to the antibodies on the strip.
  • S the blue beads get stuck on the strip because there are more antibodies there, turning it blue.
• Monoclonal Antibodies can be used for cancer diagnosis and treatment as cancerous cells have antigens and the monoclonal antibodies are designed to specifically bind with these antigens. This then clumps the cells together, making it easier to see a cancerous tumour.

  This can be used for other infections in a similar way such as HIV and AIDS.
• The Side Effects of Monoclonal antibodies are fevers, low blood pressure and vomiting.
• The Advantages of Monoclonal Antibodies are:

  • They only bind to the cells that need treatment
  • Healthy cells are not affected at all
  • Could become cheaper, as treatments are based on tested technology
  • They could be used to treat a wide range of conditions
• The Disadvantages of Monoclonal Antibodies are:

  • The process is difficult
  • Developed 40 years ago, they are not widely used.
  • Side effects
  • Expensive to develop
  • Monoclonal antibodies made by mice caused immune response in humans as the human immune system didn't recognise them.
• First Line of Defence:

  • Skin acts as a barrier to pathogens. It also secretes antimicrobial substances, which kill pathogens.
  • Hairs and mucus in your nose trap particles that could contain pathogens.
  • The trachea and bronchi secrete mucus to trap pathogens.
  • The trachea and bronchi are lined with cilia. These are hair-like structures, which waft the mucus up to the back of the throat where it can be swallowed.
  • The stomach produces hydrochloric acid. This kills pathogens that make it that far from the mouth.
• Second Line of Defence (Immune System):

  • White blood cells travel around your blood and look for microbes.
• • Phagocytosis
  • Engulfing and digesting foreign cells
• • Producing Antibodies
  • When some types of white blood cell come across a foreign antigen, they will start to produce antibodies to lock on to the invading cells so they can be found and destroyed by other white blood cells. The antibodies are specific to that antigen.
  • Antibodies are then produced rapidly and carried around the body to find all similar bacteria or viruses.
  • If the person is infected with the same pathogen again, the white blood cells will rapidly produce antibodies to kill it. The person is naturally immune to that pathogen.
• • Producing Antitoxins
  • Counteract the toxins from the pathogen
• Vaccination Pros:

  • Control lots of communicable diseases.
  • Big outbreaks of disease (epidemics) can be prevented if a large percentage of the population is vaccinated. This causes herd immunity, where the disease can’t get to people as lots of people are already vaccinated.
• Vaccination Cons:

  • Don’t always work
  • Can have a bad reaction
• Monoclonal antibodies can be used in labs and research:

  • Bind to the specific molecules you’re looking for.
  • Test blood samples for certain pathogens.
  • Bind to hormones and other chemicals in blood to measure their levels.
• Plant Diseases:

  Mineral Ions:

  • Nitrates are needed to make proteins and therefore for growth. A lack of nitrates causes stunted growth.
  • Magnesium ions are needed for making chlorophyll, which is needed for photosynthesis. Plants without enough magnesium suffer from chlorosis and have yellow leaves.
• Plant signs of disease:

  • Stunted Growth
  • Spots on the leaves
  • Patches of decay (rot)
  • Abnormal growths, e.g. lumps
  • Malformed stems or leaves
  • Discolouration