diseases

• what is communicable disease?


  a disease caused by a pathogen which can be passed between animals or plants
• what is a pathogen?


  a pathogen is a microorganism that enters the body and causes communicable diseases
• how do bacteria cause disease?


  once inside the body, they divide rapidly by binary fission

  they kill cells and produce harmful toxins
• how do viruses cause disease?


  they invade and reproduce inside body cells, leading to cell damage
• what are the 3 ways pathogens can spread?


  • by air (droplets in coughs or sneezes)
  • by water (drinking or bathing)
  • by direct contact (touching surfaces)
• how can we prevent the spread of pathogens?


  • hygiene (handwashing, disinfectants)
  • destroying vectors
  • isolation
  • vaccination
• why is it important to prevent the spread of viral diseases?


  scientists have not yet developed cures for many viral diseases
• what are the four types of pathogens?


  • bacteria
  • fungi
  • virus
  • protists
• whats bacteria?


  reproduces quickly, produces toxins and damage cells
• what are viruses?


  smaller than bacteria, lives inside your cells and replicates it
• what is a protist?


  multicelluar, lives in the cells, carried by vectors
• what is fungi?


  has hyphae that grow and penetrate on skin
• some examples caused by a virus

  • aids by HIV
  • flu of influenza
  • measles that contagiously spread through air
• how are measles transmitted?


  droplets from coughs and sneezes
• how is HIV transmitted?


  exchange of body fluids by sexual contact or sharing needles
• how can the spead of HIV/AIDS be prevented?


  • use of condoms
  • not sharing needles
  • use of antiretroviral drugs
• what is tobacco mosaic virus?


  a plant pathogen which causes leaf discolouration when cells are damaged. affected areas cannot photosynthesise.

  as there are no treatments, farmers grow TMV-resistant crop strains to avoid infection
• how is tobacco mosaic virus spread?


  contact between infected and healthy plants. insects may act as vectors which transfers the virus between different plants
• what is salmonella?


  a type of bacteria found in raw meat, poultry and eggs. if they enter the body via food poisoning, they can affect gut bacteria
• what are the syptoms of salmonella food poisoning?


  • fever
  • abdominal cramping
  • vomiting
  • diarrhoea
• how can the spread of salmonella be limited?


  • vaccinating animals
  • keep raw meat from cooked meat
  • thoroughly cook meat
• what is gonorrhoea?


  a sexually transmitted bacterial infection caused by unprotected sex with an infected individual
• what are some symptons of gonorrhoea?


  • yellow/green discharge from genitals
  • painful urination
• how to control the spread of gonorrhoea?


  through the use of antibiotics and using condoms
• what is rose black spot?

  a fungal disease which causes purple or black spots to develop on rose leaves/ it reduces the area of the leaf which is available for photosynthesis and cause leaves to turn yellow and drop prematurely
• how is rose black spot fungus spread?


  fungal spores are spread by the wind and in water
• how can rose black spots be treated?


  • using fungicides
  • destroying infected leaves
• what is malaria?


  a disease caused by protist pathogens carried from host to host by mosquitoes and the protists enter the human bloodstream when they feed
• what are symptoms of malaria?


  • fevers
  • shaking
  • fatal
• how can the spread of malaria be reduced?

  • using insecticides
  • using insect nets to avoid biting
  • prevents mosquito breeding by removing stagnant water
• how does skin prevent pathogens from entering the body?


  • acts as a physical barrier
  • scab formation after skin is cut or wounded
• how does the respiratory system prevent pathogens from entering the body?


  • nose - has hairs and mucus which traps pathogens
  • trachea and bronchi - has mucus that traps pathogens, ciliated cells move mucus to the mouth so it can be swallowed
• how does the stomach prevent pathogens infecting the body?


  • secretes hydrochloric acid- kills any pathogens present
• how does phagocytosis protect us against disease?


  white blood cells ingest and destroy pathogens so they cannot infect more cells
• how does antibody production protect us against disease?


  white blood cells produce antibodies which are complementary to a specific antigen on a pathogen. the binding of antibodies to antigens cause pathogens to clump together, making them easier to destroy
• how does antitoxin production protect us against disease?


  antitoxins bind to toxins released by pathogens and neutralise them
• what is vaccination?


  contains dead or inactivated form of pathogens which stimulates white blood cells to produce complementary antibodies to the pathogen
• how do white blood cells fight a second infection?


  memory cells are made that can rapidly produce the correct antibodies and prevent illness
• what is herd immunity?


  if a sufficiently high proportion of a population are immune to a disease through vaccinations, the spread of the disease will be limited
• what are the advantages of vaccinations?


  • they have eradicated many deadly diseases
  • many epidemics can be prevened
  • herd immunity protects those who cannot havev vaccinations