Infection and response

• What is a communicable disease?

  A disease that can be transfered from one organism to another
• What are pathogens

  Microorganisms that cause disease
• 4 types of pathogen

  Bacteria

  Fungi

  Protists

  Viruses
• How can pathogens be spread

  Air

  Water

  Contact
• How do bacteria make you ill

  Produce toxins that damage tissues
• How do virsues make you ill

  Reproduce rapidly inside cells, damaging or destroying them
• 4 ways to control spread of disease

  Hygiene, isolation, controlling vectors, vaccination
• How do you control the spread of disease by hygiene

  Hand washing, disenfecting surfaces
• How do you control the spread of disease by isolation

  Isolate infected individuals so they cant infect more people
• How do you control the spread of diseases by controlling vectors

  Destroying or controlling the population of disease carrying vectors
• How do you control the spread of diseases by vaccination

  Make a large population immune to diseases
• Vaccination

  Inject small quantities of dead or inactive forms of a pathogen into the body

  This stimulates lymphocytes to produce the correct antibodies for that pathogen

  If the same pathogen re-enters the body, the correct antibodies can be produces quickly to prevent infection
• Herd immunity

  When most of a population is immune to a disease it is less likely to spread
• What is the function of white blood cells+ what r the types

  To fight pathogens

  2 types: lymphocytes and phagocytes
• How do lymphocytes fight pathogens

  Antitoxins: lymphocytes produce antitoxins that bind to toxins and neutralise them

  Antibodies: lymphocytes produce antibodies that destroy specific pathogens by binding to antigens
• How do phagocytes fight pathogens

  1. they are attracted to areas of infection
  2. Phagocyte surrounds pathogen + engulfs it
  3. Releases enzymes that digest and destroy the pathogen
• What is an antibiotic

  A drug that kills bacteria but not viruses
• What do painkillers do

  treat some symptoms of diseases and relieve pain
• What factors are new drugs tested on + definitions

  Toxicity - is it harmful

  Efficacy - does it work

  Dose - what amount is safe and effective to give
• Stages of clinical trials

  1. Preclinical trials
  2. Clinical trials (2 stages)
  3. Peer review
• Pre-clinical trials

  Drug is tested in cells, tissues and animals
• Clinical trials stage 1

  Healthy volunteers receive low doses to test toxicity and efficacy
• Clinical trials stage 2

  If the drug is safe larger numbers of healthy volunteers and patients receive the drug to find the optimum dose
• Peer review

  Before being published the results of the clinical trials are checked by independent researches
• Double blind trials

  Some patients are given a placebo and both doctors and patients dont know who has been given the real drug

  This reduces biases in the trial
• How does the skin protect against pathogens

  Physical barrier to infection

  Produces antimicrobial secretions
• How does the nose prevent against pathogens

  Cilia and mucus trap particles in the air
• How does the stomach prevent against diseases

  Produces strong stomach acids (ph 2) that destroys pathogens
• Discovering and developing new drugs

  Drugs were traditionally extracted from plants and microorganisms

  For example penicillin came from penicillium mould

  Modern drugs are now synthesised by chemists in laboratories
• What are non communicable diseases

  Conditions that cannot be directly transmitted from one person to another
• Measles

  Viral disease

  Spread by: inhalation of droplets produced by infected people sneezing and coughing

  Symptoms: Fever, red skin rash, complications can be fatal

  Prevention and treatment: Painkillers, vaccinations
• HIV

  Viral disease

  Spread by: exchange of body fluids such as sexual contact or blood when drug users share needles

  Symptoms: Flu like symptoms, virus attacks body can lead to AIDS

  Prevention and treatment: antiretroviral drugs, barrier methods, using clean needles
• TMV

  Viral disease

  Spread by: Direct contact of plants with infected plant material, animal and plant vectors, soil

  Symptoms: mosaic pattern of discolouration on leaves, reduces plants ability photosynthesis

  Prevention and treatment: Removing infected plants
• Salmonella

  Bacterial disease

  Spread by: Bacteria in or on food being ingested

  Symptoms: Fever, abdominal cramps, vomiting, diarrhoea

  Prevention and treatment: Poultry are vaccinated against salmonella
• Gonorrhoea

  Bacterial disease

  Spread by: direct sexual contact

  Symptoms: Thick yellow or green discharge, pain when urinating

  Prevention and treatment: antibiotics, barrier methods
• Rose black spot

  Fungal disease

  Spread by: Water and wind

  Symptoms: Purple or black spots on leaves, reduces plants ability to photosynthesise

  Prevention and treatment: Fungicides, affected leaves removed and destroyed
• Malaria

  Protist disease

  Spread by: mosquitos

  Symptoms: Recurrent episodes of fever, can be fatal

  Prevention and treatment: Mosquito nets, anti-malarial medicine
• Factors that can affect health

  Diseases

  Diet

  Stress

  Exercise

  Life situations