pathogens

• define pathogens?


  microorganisms that cause infectious diseases like bacteria, viruses, protists and fungis
• how does bacteria make us ill? - 2 steps

  1. once in body bacteria reproduces rapidly
  2. #then bacteria releases harmful chemicals= toxins= damages tissues and makes us feel ill
• what are viruses?


  Viruses live and reproduce inside cells, causing cell damage
• how do viruses make us ill?


  virus invades the host cell now virus reproduces inside the host cell - very damaging to the cell when virus leaves the cell, it can cause the cell to burst open and die
• how can pathogens spread?


  in air e.g. water droplets (influenza)in water (cholera) when drinking sewage water direct contact between indiviuals (HIV)
• How can HIV be spreaded?

  when drug users share infected needles , sexual contact
• how to reduce the spread of pathogens?

  1. washing hands before eating
  2. clean drinking water- UK water contains chlorine= kills microbes-
  3. using condoms during sex = reduces spread of HIV
  4. people with highly infectious diseases such as ebola are required to self isolate = reduces the spread of the contagious disease
  5. vaccinations
• White blood cells are produced by bone marrow and circulate around the body in the bloodstream.
• There are two types of white blood cell - phagocytes and lymphocytes
• Lymphocytes produce antibodies that bind to specific antigens on the surface of pathogens
• Phagocytes engulf foreign particles including bacteria and dead or damaged cells
• what is the process of phagocytes ?


  they engulf pathogens and bind to them. The phagocytes membrane surrounds the pathogen and enzymes found inside the cell break down the pathogen in order to destroy it.
• what happens when the skin is damaged?

  1. pathogens invade the body and enter the bloodstream
  2. once in the body pathogens can multiply and damage healthy tissue - bacteria releases toxins
• what is the immune system?

  destroys pathogens and any toxins they produce

  AND protects us from pathogens that once invaded us
• functions of the WBC : PHAGOCYTOSIS

  1. ingest and destroy pathogens
  2. WBC detects chemicals released from the pathogen and moves towards it
  3. ingests the pathogens
  4. uses enzymes to destroy the pathogens
• what are antibodies?


  protein molecules produced by WBC

  1. WBC releases antibodies
  2. antibodies stick to the pathogens
  3. this triggers the pathogens to be destroyed
• are antibodies specific?


  yes they will only protect you from the specific pathogen
• TRUE OR FALSE- ANTIBODIES DONT REMAIN UR BLOOD FOR A LONG TIME

  false - they can protect us incase we get infected again with the same pathogen
• what are antitoxins?


  stick to toxin molecules and prevent them from damaging cells