Infection and Response

• What are communicable diseases caused by?

  biological agents / pathogens
• How are non-communicable diseases developed?

  Lifestyle factors

  • environmental
  • genetic
  • behavioural
• What are the 2 types of risk factors?

  • Ones we can’t control - genes, age
  • Ones we can control -diet, exercise
• What is health?

  a state of physical and mental wellbeing
• What is the difference between consequence and probability?

  consequence - effects of disease e.g. cold has low consequence

  probability - chance of catching it e.g. cold has high probability
• Risk is a product of: ?


  probability of event * impact of event
• What is a causal mechanism?

  a risk factor partially responsible for a disease
• What is causation?

  definite cause, proven
• what is correlation?

  not proven cause, link
• What are the 4 main groups of pathogen?

  • Virus - e.g. Covid, measles
  • Bacteria - e.g. salmonella
  • Protists - e.g. malaria
  • Fungus - e.g. athletes foot, black spot
• How do pathogens spread between individuals?

  • Airborne transmission - e.g. coughs, sneezes
  • Contaminated food/water - e.g. undercooked meat
  • Direct contact - e.g. touching
  • Indirect contact - e.g. touching an object someone else has touched
  • Vector - e.g. flies, mosquitos
• How can we reduce the spread of pathogens?

  • good respiratory hygiene - e.g. wearing masks, using using tissue
  • vaccines
  • control vectors
  • cook food properly
  • sanitise and sterilise objects
• What are some differences between bacterial pathogens and viral pathogens?

  Bacteria - living cells

  Virus - dead cells

  Bacteria - 1/2 micrometers

  Virus - 50nm

  Bacteria - replicate by binary fission (outside host cell)

  Virus - Use content of host cell to make new viruses
• How do the pathogens have different effects on the body?

  Bacteria - produces toxins, causes cell damage / death, makes you feel ill

  Virus - causes cell death, triggers body’s immune response, makes you feel ill
• Can a bacterial cell be treated with antibiotics?

  Yes - it lives outside host cell so can be found easily
• Can a viral pathogen be treated with antibiotics?

  No - it hides inside host cells
• What do disinfectants do?

  destroy cells including bacteria
• What do antiseptics do?

  destroy bacteria without damaging body cells
• What is done before clinical trials?

  Preclinical trials - testing using cells, tissues and animals
• Phases of clinical tests

  1 - Low doses given to a small number of healthy volunteers

  To test safety / for side effects

  2 - Different doses given to a small number of suffering patients

  To find optimum dose and efficacy

  3 - larger number of patients over a longer time with placebo

  To test if it’s better than the original drug
• What drug comes from foxglove?

  digitalis
• What drug comes from a willow tree?

  aspirin
• What is drug comes from mould?

  penicillin
• What is herd immunity?

  when most people are vaccinated and the pathogen can’t spread
• What do memory cells do?

  They trigger a secondary immune response that is faster and longer
• What is a drug?

  any chemical that alters how the body works
• What is a recreational drug?

  A drug used for pleasure
• What is a medicinal drug?

  a drug used to treat an illness
• What is an antibiotic?

  a drug that destroys bacteria or inhibits cell processes
• What do antibiotics do?

  Block the small ribosomes, so the bacteria can’t reproduce without protein. They can do this because animal cells have large ribosomes and can not be harmed
• What do bacteriocidal

  antibiotics do?

  Rupture the cell wall, causing the cell to burst
• Why does antibiotic resistance occur?

  Mutation of bacterial DNA allows new strains of bacteria to be produced, which may have some resistance
• What causes antibiotic resistance?

  the wrong use of antibiotics

  • using when not needed
  • using for viral infections (it won’t work)
• Antibiotic Resistance

  
• Explain how natural selection could have produced these strains of antibiotic resistant bacteria

  Due to genetic mutations, there is a variation I’m a population of bacteria, so some may randomly mutate to become resistant to the antibiotic. When the popul is treated with the antibiotic, only the highly resistant bacteria survive, and these then reproduce and replicate themselves through binary fission. The gene for resistance is passed on to the offspring.
• Percentage change formula

  %change = difference/total * 100
• What are the symptoms of measles?

  • high fever
  • red rash
  • coughing and sneezing
• What are the symptoms of HIV?

  • flu like symptoms
  • can cause AIDs
• What are the symptoms of tobacco mosaic virus?

  • discolouration on leaves
  • affects growth
• Symptoms of salmonella

  • fever
  • abdominal cramps
  • vomiting
  • diarrhoea