Infection and Response ( Paper 1 )

• Pathogen : Microorganisms that cause disease
• There are 4 types of Pathogens
• The types of Pathogens -

  • Bacteria
  • Virus
  • Fungi
  • Protists
• Pathogens can be spread by -

  • direct contact ( touch )
  • In the air
  • In water and food - contamination
• Why do Viruses make us feel unwell?

  They reproduce in a cell and when it bursts, that is when it infects us and others
• Why does Bacteria make us feel unwell?

  Releases toxins into our body
• What is a communicable disease?

  A communicable disease is an illness that is infectious and can spread to others
• What is a Non - communicable disease?

  A non - communicable disease is an illness that isn't infectious and cannot be spread from others
• Communicable disease:

  • Covid - 19
  • HIV
  • Chicken Pox
  • Malaria
• Non - communicable disease:

  • Asthma
  • Diabetes
  • Cancer
  • Heart Disease
• How can you prevent the spread of communicable diseases?

  • Vaccination
  • Isolation
  • Hygiene
  • Controlling Vectors
• Types of Viruses

  • Measles
  • HIV ( human immunodeficiency virus )
  • TMV ( tobacco mosaic virus )
• Types of Bacteria

  • Salmonella
  • Gonorrhoea
• Types of Fungi

  • RBS ( rose black spot )
• Types of Protists

  • Malaria
• TMV ( tobacco mosaic virus ) - Virus

  Spread by?

  • Direct contact of plants or from the farmer touching other plants
  • Naturally through the soil

  Symptoms?

  • Mosaic pattern and discolouration of the leaves - chlorophyll is destroyed - reduces the plants ability to photosynthesise

  Prevention?

  • Remove infected plants

  Treat?

  • No Cure
• Measles - Virus

  Spread by?

  • Inhalation of droplets from infected peoples sneezes and coughs

  Symptoms?

  • Red skin rash
  • Flu-like

  Prevention?

  • Young children get vaccinated against it
• HIV ( human immunodeficiency virus ) - Virus

  Spread by?

  • Sexual contact
  • Exchange of bodily fluids like blood when drug users share needles

  Symptoms?

  • Flu-like ( fever, diarrhoea, fatigue )
  • Can progress to AIDS

  Prevention?

  • Use condoms
  • Never share needles, syringes and swabs etc.
• Salmonella - Bacteria

  Spread by?

  • Consumption of contaminated food ( meat, eggs, milk etc. )
  • Food prepared in unhygienic conditions

  Symptoms?

  • Fever
  • Abdominal Cramps
  • Nausea
  • Vomiting
  • Diarrhoea

  Prevention?

  • Vaccination of animals
  • Make sure everything has been thoroughly cleaned
• Gonorrhoea - Bacteria

  Spread by?

  • It is an STD ( sexually transmitted disease )

  Symptoms?

  • Thick yellow or green discharge from the vagina or penis
  • Pain when urinating ( dysuria )

  Prevention?

  • Treatment with antibiotics
  • Using contraception such as a condom
• RBS ( rose black spot ) - Fungi

  Spread by?

  • Water
  • Wind
  • Contact from gardeners

  Symptoms?

  • Black or purple spots on leaves
  • Leaves turn yellow and drop off the plant

  Prevention?

  • Treat using fungicides
  • Remove and destroy infected leaves
• Malaria - Protist

  Spread by?

  • mosquitoes that feed on an infected person and then spread the pathogen when feeding on another person - these are called vectors

  Symptoms?

  • Recurrent fever

  Prevention?

  • Prevent the mosquitoes ( vectors ) from breeding
  • Mosquito nets to prevent bites
• What does a vaccine contain?

  Dead or inactive versions of that pathogen that your being vaccinated against
• Stages of vaccination:

  1. Injecting dead or inactive forms of a pathogen into the body
  2. This triggers an immune response - lymphocytes produce specific antibodies for that pathogen
  3. The body remembers these antibodies as memory cells for when the same pathogen re enters the body
  4. If the same pathogen re enters the body, memory cells recognise the pathogen so your immune system starts to produce antibodies quickly, killing the pathogen to prevent infection.
• White blood cells

  • Lymphocytes
  • Phagocytes
• Lymphocytes:

  • Antibodies - bind to antigens, bind to pathogens to clump them together, they are specific
  • Antitoxins- bind to the toxins produced by some pathogens (bacteria) neutralising them
• Phagocytosis:

  1. Phagocyte recognises pathogen
  2. The membrane of the phagocyte extends around the pathogen
  3. The phagocyte engulfs the pathogen and contains it
  4. The phagocyte releases enzymes (lysozymes) which breaks down the pathogen

  
• Penicillin is an antibiotic that originates from mould - Alexander Fleming
• Digitalis - heart drug that originates from foxgloves
• Aspirin - painkiller that originates from willow tress
• What is a placebo?

  A fake drug
• Clinical trials -

  Blind trial: The volunteer doesn't know if they have the placebo or the real drug

  Double blind trial: Neither the volunteer or the doctor knows who has the placebo or the real drug
• What is the purpose of a double blind trial?

  Avoid bias
• What are the effects of the placebo?

  Psycholofical effect
• What medicine treats disease?

  Antibiotics kill bacteria in the body

  Viruses cannot be treated with antibiotics because they are contained within healthy cells - the antibiotic will kill the healthy cell aswell as the virus
• The bodys defences against pathogens:

  1. Skin - physical barrier
  2. Nose - Cilia and mucus trap particles in the air
  3. Stomach - Produces acid that kills pathogens
• Monoclonal Antibodies:

  1. Inject a mouse with antigens
  2. This stimulates the mouse's lymphocytes to produce antibodies specific to the antigen
  3. Combine the antibodies with a tumour cell - hybridoma
  4. Clone the hybridoma to make more specific antibodies
  5. Collect antibodies

  A) Tumour cells

  B) antibodies ( lymphocytes )

  
• Use of moncoclonal antibodies:

  • Pregnancy tests
  • Research and diagnosis
  • Cancer treatment
• Tumours:

  • Malignant = cancerous, not incapsulated
  • Benign = not cancer, capsulated
• How do tumours spread?

  Cells reproduce and travel through the bloodstream to other parts of the body