Unit 10

• Pathogen


  An organism that causes disease
• Pathogens


  • Bacteria
  • Viruses
• Host


  Organisms which harbour pathogens
• Transmissible diseases


  Diseases that can be spread from host to host through contact with an infected organism, or through other mediums such as food, water, waste and bodily fluids
• Preventing the spread of disease

  1. Preparing food hygienically

  2. Treating waste and sewage

  3. Maintaining good personal hygiene
• Body's first line of defense against infection

  • Mechanical barriers (hairs in the nose and skin)
  • Chemical barriers (mucus, stomach acid and tears)
• Immune response

  The body's response to kill pathogens, involving phagocytosis and antibody production by white blood cells
• Antigen


  Specific protein on the cell membrane of a pathogen
• Antibody


  Produced by lymphocytes to bind to antigens and form an antibody-antigen complex
• Antibody binds to antigen

  Pathogens clump together and are made harmless, then killed directly or marked for destruction by phagocytes
• Autoimmune disease


  Disease caused by an immune response on healthy body cells, which are targeted and destroyed by the immune system
• Autoimmune disease


  • Type 1 diabetes
• Active immunity


  Immunity gained after an infection or through vaccination, involving memory cells that can produce antibodies more quickly if the pathogen enters the body again
• Gaining active immunity through vaccination

  1. Give a dead or attenuated version of a pathogen

  2. Antigens evoke an immune response, producing antibodies

  3. Memory cells are produced, giving long-term immunity
• Herd immunity


  When a large amount of the population is vaccinated and thus immune to a pathogen, preventing the disease from spreading
• Passive immunity


  Short-term defense against a pathogen gained through acquiring antibodies from another individual, such as from a mother's milk or antibody injections
• Passive immunity does not involve the production of memory cells
• Drug


  A substance that, when taken into the body, has an effect on the chemical reactions that take place
• Types of drugs


  • Antibiotics
  • Alcohol
  • Heroin
  • Anabolic steroids
  • Testosterone
  • Nicotine
• Antibiotics


  • Used to treat bacterial infections
  • Some kill bacteria by destroying their cell wall
  • Others inhibit the growth of bacteria
  • Cannot kill viruses
• Development of antibiotic resistance

  1. Mutation occurs in a bacterial cell making it resistant

  2. Resistant cell survives when antibiotic is administered

  3. Resistant cell reproduces, producing more resistant bacteria
• Antibiotic resistant bacterial infections

  Infections such as MRSA in hospitals
• It is important to try and slow the development of resistant bacterial strains
• Depressants


  Drugs that lower the rate of nervous impulses by blocking synapses, leading to slower reactions and lower self-control
• Addiction


  Caused by the release of neurotransmitters like dopamine into the reward pathway, leading to withdrawal symptoms if the drug is stopped
• Performance-enhancing drugs


  • Used to enhance sporting performance
  • Usually banned in competitive sports
• Anabolic steroids


  Trigger the release of hormones that promote muscle mass and strength
• Testosterone


  Hormone that enhances athletic performance by improving muscle strength and size, as well as increasing energy levels and hand-eye coordination
• Smoking


  • Addictive due to nicotine
  • Linked to many diseases
• Chronic obstructive pulmonary disease (COPD)

  Group of diseases that decrease the efficiency of gas exchange in the lungs, causing breathlessness, persistent cough and frequent chest infections
• Lung cancer


  One of the more serious forms of cancer, for which smoking accounts for over 85% of cases
• Coronary heart disease


  Smoking puts a strain on the heart due to nicotine and carbon monoxide, increasing the risk of blood clots and artery damage, leading to heart attacks and heart failure
• Smoking is a major risk factor for diseases, but other factors also alter the probability of having them