B8 Preventing + treating disease

• Lymphocytes


  Make antibodies but cannot divide to form clones
• Vaccination


  Injecting small quantities of dead or inactive forms of a pathogen into the body
• Vaccination


  1. Stimulates lymphocytes to produce the correct antibodies for that pathogen

  2. If the same pathogen re-enters the body, the correct antibodies can be produced quickly to prevent infection
• Concentration of antibodies in blood increases after vaccination
• Dose


  What amount is safe and effective to give?
• Stages of clinical trials


  1. Pre-clinical trials: Drug is tested in cells, tissues, and live animals

  2. Clinical trials: 1. Healthy volunteers receive very low doses to test safety and efficacy, 2. If safe, larger numbers of healthy volunteers and patients receive the drug to find the optimum dose
• Peer review


  Before being published, the results of clinical trials will be tested and checked by independent researchers
• Double-blind trials


  Some clinical trials give some of their patients a placebo drug, and neither the patients nor the doctors know who has been given the real drug and who has been given the placebo
• Antibiotics are medicines that can kill bacteria in the body
• Specific bacteria need to be treated by specific antibiotics
• Antibiotics have greatly reduced deaths from infectious bacterial diseases, but antibiotic-resistant strains of bacteria are emerging
• Antibiotics do not affect viruses
• Drugs that kill viruses often damage the body's tissues
• Painkillers treat the symptoms of viral diseases but do not kill pathogens
• Most modern drugs are now synthesised by chemists in laboratories
• New drugs are extensively tested and trialled for toxicity, efficacy, and dose
• Non-specific defences of the human body against all pathogens include skin, nose, and stomach
• White blood cells fight pathogens, including lymphocytes that produce antitoxins and antibodies, and phagocytes that engulf and destroy pathogens
• Herd immunity


  If a large proportion of a population is vaccinated against a disease, the disease is less likely to spread, even if there are unvaccinated individuals
• Antibiotic resistance arises when bacteria evolve resistance, not when people become resistant to a drug