Keeping Healthy

Diet and Exercise
1. Nutrients
  1. The body needs needs a mixture of different types of food to keep healthy
    1. Our diet is split into food groups. The main ones being; Carbohydrates, Protein and Fats
      1. Carbohydrates (Bread, pasta, potatoes etc.) are responsible as a source of energy for life
      2. Proteins (Meat, Fish, Eggs etc.) are responsible for the growth and repair of cells
      3. Fats (Butter, margarine, oil etc.) act as both energy for life process as well as cell membranes for insulation
      4. Minerals and vitamins are also needed in small amounts to help the body function
2. Exercise
  1. The Metabolic rate is the speed at which a body's cells respire( release energy from food) and it varies due to gender, age and other inherited factors
    1. A person's metabolic rate is affected by the proportion of muscle to fat in their body and the amount of exercise they do
3. Cholesterol
  1. Cholesterol is made in the liver and is needed for healthy cell membranes
    1. Too much cholesterol in the blood increases the risk of heart disease and diseased arteries
4. Diet
  1. A healthy diet and plenty of exercise is needed for a healthy body. This is called malnourished.
    1. Too little food will lead to being underweight and makes the body more prone to certain illnesses
      1. A deficiency of vitamin D can lead to rickets.
    2. Too much food and not exercise will lead to being underweight and makes the body more prone to other certain types of illnesses
      1. Too much sugar can lead to type 2 diabetes.
Defending Against Infection
1. Pathogens
  1. Pathogens are micro-organisms that cause disease and exist as either bacteria or viruses
    1. Pathogens contain certain chemicals called antigens that are foreign to the body
  2. Bacteria
    1. Once inside the body, bacteria release toxins that make us feel ill
    2. Bacteria, once in favourable conditions are able to rapidly multiply
    3. Bacteria are able to disease the human body with food poisoning, cholera, typhoid and whooping cough
  3. Viruses
    1. Viruses are a lot smaller than bacteria and only reproduce in host cells which damages the cell
      1. Once in a cell, a virus can take over the cell and making hundreds of thousands copies of itself
        Once the cell is filled with copies, it bursts and the viruses are passed out by the blood stream and airway
    2. Viruses can cause influenza, colds, measles, mumps, rubella, chicken pox and AIDs
  4. Immunity
    1. Antibodies
      1. White Blood Cells
        White blood cells ingest pathogens
        Antitoxins are specialised proteins produced to counteract toxins released by the pathogens
        Certain white blood cells called Lymphocytes can produce specific antibodies to kill particular pathogens
        Each lymphocyte produces a specific type of antibody - a protein that has a chemical 'fit' to a certain antigen. When a lymphocyte with the appropriate antibody meets the antigen, the lymphocyte reproduces quickly and makes many copies of the antibody to kill the pathogen.
      2. Antibodies are specialised proteins produced to kill particular pathogens
        Antibodies can either coat pathogens, clumping them together so that they are easily ingested by white blood cells called phagocytes or bind to pathogens and damage/destroy them
    2. Vaccination
      1. Different vaccines are needed for different pathogens e.g the MMR vaccine is used to protect children against measles, mumps and rubella (German measles)
      2. Vaccination involves putting a small amount of an inactive form of a pathogen, or dead pathogen, into the body
        Vaccination causes the body to produce enough white blood cells to protect itself against a pathogen
        This means that if they do ever contract the pathogen, they will have the right antibody to stop it
    3. Hygiene
      1. In the 19th century Semmelweiss discovered that the washing of hands could greatly reduce the number deaths by infectious diseases in hospitals
2. Medication
  1. Painkillers
    1. Painkillers do not kill pathogens but relieve the symptoms of a diseases
  2. Antibiotics
    1. Antibiotics are substances that kill bacteria or stop their growth
      1. They do not work against viruses because they live and reproduce inside cells
    2. It is difficult to develop drugs that kill viruses without also damaging the body’s tissues
    3. Penicillin, the first antibiotic, was discovered in 1928 by Alexander Fleming. He noticed that some bacteria he had left in a Petri dish had been killed by naturally occurring penicillium mould. Since the discovery of penicillin, many other antibiotics have been discovered and developed
    4. Antibiotic Resistance
      1. Bacterial strains can develop resistance to antibiotics. This happens because of natural selection. In a large population of bacteria, there may be some cells that are not affected by the antibiotic. These cells survive and reproduce, producing even more bacteria that are not affected by the antibiotic
      2. MRSA
        Methicillin-resistant Staphylococcus aureus is a strain of bacterium which is immune to most antibiotics
      3. To slow down the development of antibiotic resistant strains we should always avoid the unnecessary use of antibiotics and complete the full course
      4. The main steps in the development of resistance are:
        1. Antibiotics kill individual pathogens of the non-resistant strain.
        2.Resistant individual pathogens survive and reproduce
        3.The population of the resistant pathogens increases
3. Growing Micro-organisms in the lab
  1. Uncontaminated cultures of micro-organisms are required for investigating the action of disinfectants
    1. To do this you must:
      1. 1. Sterilise Petri dishes and culture media (Agar Jelly etc.) before use to kill unwanted micro-organisms
        2. Sterilise inoculating loops by passing through a frame
        3. Secure lid of Petri dish with adhesive tapes to prevent micro-organisms from the air contaminating the culture
  2. Heightened temperatures are likely to increase growth and is therefore dangerous close to 37 degrees centigrade as it might allow the growth of pathogens harmful to health
    1. School labs are limited to 25 degrees centigrade incubation

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Keeping Healthy

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