infectious diseases

• communicable disease=

  can be spread person to person by pathogens
• non communicable diseases=

  cant be spread person to person
• define health

  a state of physical and mental well being
• what is tuberculosis,, how does body fight it


  a communicable lung disease,, most peoples immune system fights off the TB- some have a defective immune system, so more likely to be effected from other diseases
• HPV

  • extremely common and most cases- harmless
  • in some cases can cause cervical cancer
• allergies are triggered by the....

  immune system
• define pathogen

  microorganisms that cause infectious disease
• how does bacteria make us ill?

  once inside the body, bacteria reproduces very rapidly

  can divide every 20 mins

  bacteria can release harmful chemicals called toxins
• what do toxins do

  • damage tissues
  • make us feel ill
• viruses cannot...

  reproduce by themselves, they need a host cell
• whys it dangerous when a virus enters the host cell

  • it reproduces
  • therefore damaging the cell as..
  • when the virus leaves the cell, it can cause the cell to burst open and die.
• name the 3 ways pathogens can be spread

  1. in the air
  2. directly in water
  3. direct contact
• name the 5 ways we can reduce the spread of pathogens

  1. practicing hygiene(washing hands)
  2. clean drinking water
  3. protected sexual intercourse
  4. isolation(highly dangerous diseases)
  5. vaccination
• what is the symptom of measles

  fever

  then skin rash
• how is measles spread

  through air, in droplets when an infected person coughs or sneezes
• what are the stages of HIV

  flu like illness

  leaves after 2-3 weeks

  at that point the virus is attacking the patients immune system

  overtime immune system becomes severely damaged and cant fight off other infections

  including cancer

  highly damaged immune systems leads to patient being pone to disease, easily catching TB or even cancer
• how can you treat a person infected with HIV

  antiretroval drugs stop virus from multiplying- not a cure, lifelong prescription
• How does HIV spread

  unprotected sexual intercourse

  when drug users share infected needles (blood)
• the bacteria that causes salmonella food poisoning are spread by...

  ingesting infected food
• what cause the symptoms of salmonella

  harmful toxins
• gonorrhoea is a...


  sexually transmitted disease (STD)
• symptoms of gonorrhoea


  thick yellow/green discharge

  pain whilst urinating
• treatment of gonorrhoea in the past.. problems now...

  easily treated by penicillin

  antibiotic resistant strains of bacteria are now common
• gonorrhoea prevention 


  use condom during sex- stops transmitting

  if not, get tested and take antibiotics to kill the bacteria before they pass it on to another person
• malaria pathogen is an example of a...

  protist
• life cycle of malaria

  1. infected person is bitten by a mosquito
  2. malaria pathogen now enters into mosquito, making it a vector
  3. vector now bites a different person and passes the malaria pathogen to them
  4. cycle repeats
• what are the 2 main ways of stopping the spread off malaria

  1. stop the vector from breeding- drain still water ponds where they usually breed
  2. prevent mosquitos from biting humans- nets for sleeping, spray with insecticide
• what is the job of the non specific defence system

  prevent pathogens from entering the human body
• 4 main parts of the non-specific defence systems

  1.skin

  2.nose

  3.lungs

  4.stomach
• describe the defence system skin

  produces an oily sebum which can kill bacteria

  skin scabs over open wounds to prevent pathogens to enter
• describe the defence system nose

  contains hair and mucus, traps pathogens before they enter
• describe the defence system lungs

  cilia covered in mucus that can trap pathogens

  cilia wafts the mucus upwards towards the throat where it is swallowed into the stomach
• describe the defence system stomach

  hydrochloric acid inside stomach kills pathogens before they can enter their way further down the digestive system
• describe the 2 main functions of the immune system

  1. destroy pathogens and any toxins they produce
  2. protects us in case the same pathogen invades again in the future
• describe phagocytosis

  1. white blood cell detects chemical released from pathogens
  2. moves towards the pathogen
  3. then ingests the pathogen
  4. wbc uses enzymes to destroy the pathogens
• antibodies are...


  protine molecules produced by white blood cells
• antibodies against pathogens..


  wbc releases antibodies

  antibodies stick to the pathogens

  this triggers the pathogens to be destroyed
• antitoxins


  wbc produce antitoxins

  sticks to toxin molecules

  prevents them from damaging cells.
• how do vaccines work?

  • dead or inactive forms of the pathogen is introduced into the body
  • because the pathogen isnt active, it wont harm patient
  • white blood cells produce antibodies against the pathogen
  • at the sme time, white blood cell is defended by mitosis to produce lots of copies of itself
  • thee copies stay in the blood for decades
  • now if pathogen enters body again, wbc can produce antibodies quickly, preventing infection.
• herd immunity definition


  very large number of people vaccinated against pathogens

  if enough people are vaccinated, the un-vaccinated people are now also protected