Disease

• Disease


  Disease causes health problems by affecting an organism's body, organs, tissue or cells
• Types of disease

  • Communicable
  • Non-communicable
• Communicable disease

  Contagious, spread by pathogen
• Non-communicable disease

  Not contagious, caused by genetics and lifestyle
• Non-communicable diseases examples


  • Chronic lung disease
  • Cancer
• Pathogens


  Microorganisms (Microbes) that cause diseases
• Types of Pathogens

  Bacteria, Viruses, Fungi, Protists
• Spreading Pathogens

  Food: eg. Salmonella

  Air: eg. Covid 19

  Water: eg. Cholera

  Direct contact: eg. Athlete's foot

  Vectors: eg. Malaria
• Salmonella


  Caused by Bacteria

  Symptoms: fever, vomit, diarrhoea

  Treatment: poultry are vaccinated against it
• Gonorrhoea


  Caused by Bacteria

  Symptoms: thick yellow or green discharge, pain on urinating

  Treatment: penicillin
• Measles


  Caused by viruses

  Symptoms: high fever, red skin rash

  Treatment: none
• HIV/Aids


  Caused by viruses

  Symptoms: flu like symptoms

  Treatment: antirovial drugs
• Tobacco mosaic (plants)


  Caused by viruses

  Symptoms: less chlorophyll in the affected parts

  Treatment: none
• Rose blackspot (plants)


  Caused by fungus

  Symptoms: purple or black spots develop on leaves

  Treatment: remove infected leaves, fungicides
• Malaria


  Caused by protists

  Symptoms: recurring fevers, shaking

  Treatment: preventing vectors from breeding
• Bacteria and viruses may reproduce rapidly inside the body. There are two main ways that microbes make people ill:

  1. All microbes damage and kill cells in your body. This causes pain and stops your body from working properly.
  2. Some microbes produce toxins which damage the way your cells work or damage and kill tissues.
• The immune system


  Like most cells, pathogens have unique molecules on their surfaces called antigens. White blood cells recognise them as different.
• Role: Ingesting microorganisms

  Phagocytes are white blood cells that ingest pathogens, enclosing them so they can't make you ill. This process is called phagocytosis.
• Role: Producing antibodies

  Some white blood cells produce antibodies. These target particular bacterias and viruses. The antibodies bind to the antigens on the surface of the pathogen. The antibodies either destroy the pathogen or cause them to clump together. They are then ingested by phagocytes. Once your white blood cells have produced antibodies against a particular pathogen , they can be made very fast if that pathogen get into the body again. You are then immune to that disease.
• Role: Producing antitoxins

  Some white blood cells produce antitoxins. These counteract (cancel out) the toxins (poisons) released by the pathogen.
• Both the white blood cells that produce antibodies and antitoxins are called lymphocytes.
• Vaccines


  A dead or inactive form of the pathogen is introduced into the body, leading white blood cells to produce antibodies to combat it. As a result, the correct antibodies can be made quickly if the pathogen re-enters the body, preventing an infection.