Topic 5

• WHO


  World Health Organisation
• Definition of health


  'a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity'
• Communicable disease


  Can be transmitted from one person to the other. Caused by a pathogen (microbe which causes a disease). Not inherited.
• Communicable diseases examples

  • measles, flu, cold
• Non-Communicable disease


  Cannot be transmitted from one person to the other. Not caused by pathogen.
• Non-Communicable diseases examples 


  • cancer, heart disease, diabetes
• Diseases


  • stomach ulcers
  • chalara
  • ash dieback
  • tuberculosis
  • ebola
  • malaria
  • cholera
  • HIV
• Cholera


  bacteria, Diarrhoea, Spreads through Water
• Tuberculosis

  bacteria, Lung damage, Spreads through Airborne
• Chalara ash dieback


  Fungi, Leaf loss, bark lesions (damage), Spreads through Airborne
• Malaria


  Protists, Damage to blood and liver, Spreads through Animal vectors (animals transmit it)
• HIV


  Virus, Destroys white blood cells leading to AIDS, Spreads through Body fluids during sex, breastmilk, needles
• Stomach ulcers


  Bacteria (Helicobacter), Stomach pain, indigestion, Spreads through Oral transmission (through saliva)
• Ebola


  virus, Causes haemorrhagic fever (fever and internal bleeding), Spreads through Direct contact with infected blood or body fluids (sex, vomit, sweat)
• Reduce or prevent the spread of Cholera


  Drink bottled/boiled water, vaccination
• Reduce or prevent the spread of Tuberculosis


  Avoid close contact, cover mouth if cough, vaccination
• Reduce or prevent the spread of Malaria


  Prevent bites e.g. mosquito net, malaria prevention tablets
• Reduce or prevent the spread of Stomach ulcers

  Antibiotics
• Reduce or prevent the spread of Ebola

  Avoid physical contact/infected body fluids, wash hands
• Reduce or prevent the spread of Chalara ash

  Remove infected trees, disinfect cutting equipment
• Antibiotics

  Medications which only kill bacteria, work by inhibiting (stopping) processes in bacterial cells e.g. stopping the cell walls being built
• STI

  Sexually transmitted infection
• How are STI's spread/transmitted?

  Mainly spread by unprotected sex
• How can the spread of STI's be reduced or prevented?

  Reduce the spread by using a barrier method of contraception e.g. condom. HIV - also don't share needles.
• Chlamydia

  Caused by a bacterium (but it reproduces inside host cells), Often symptomless -> infertility
• HIV and AIDS

  HIV (Human Immunodeficiency Virus) kills white blood cells leading to AIDS (Acquired Immune Deficiency Syndrome) where the immune system deteriorates allowing infections to occur
• Skin

  Barrier: thick covering over the body. Waterproof. Dead cells on surface. Function: prevents pathogens entering the body through the skin. If cut, blood clots forming a scab.
• Mucus/cilia

  Barrier: Mucus produced by cells lining some surfaces of the body (e.g. airways). Function: Mucus traps pathogens. Barrier: Cilia are found on cells lining the respiratory system. Function: Cilia move mucus with trapped pathogens into the throat, out of the lungs.
• Tears (eyes)

  Defence: Lysozymes are enzymes found in tears. Function: Lysozymes kill some bacteria.
• Stomach acid

  Defence: Hydrochloric acid in the stomach. Function: Hydrochloric acid has a low pH which kills many pathogens.
• Antigen

  Chemical on the surface of cells
• B lymphocyte

  White blood cell which produces antibodies
• Antibody

  Chemical which attaches onto antigens to help destroy them
• Pathogen

  Microbe which causes an infection
• Phagocyte

  White blood cell which engulfs pathogens
• Pathogen (e.g. bacteria) has an antigen on its surface which are unique to it ('label')

  B lymphocytes don't recognise the foreign antigen (on pathogen) and produce antibodies (1st response). Antibodies attach to the antigens on any more of these particular invading pathogens. Antibodies are specific to one type of antigen. During this time, symptoms will show. Other white blood cells called phagocytes engulf the pathogens. Eventually enough antibodies are made to overcome the infection. A type of B lymphocyte called memory lymphocytes are made in response to the antigens and stay in the blood. The person is now immune. If re-infected with the same pathogen, the memory lymphocytes 'remember' the specific antigen and produce antibodies very quickly and destroy the pathogen before you have symptoms - this 2nd response is faster and stronger.
• B lymphocyte
• Why are people immunised against certain pathogens and diseases?

  To exposed someone to the pathogen so they can develop immunity BEFORE catching it.
• What would need to be in the vaccine?

  Dead/inactive pathogen so the body is exposed to the antigens on the pathogen to trigger an immune response.
• Immunisations (vaccinations)

  contain dead or inactive pathogens which are usually injected into you. The antigens on their surface trigger antibodies to be made as well as memory lymphocytes. If you are infected in the future, many antibodies are made quickly to kill the pathogen before you have any symptoms.