🏥 Chapter 11 - Infectious Diseases

• disease

  • condition that causes body to function less effectively
• infectious diseases

  • can be transmitted from one person to another and caused via pathogens
  • non-infectious diseases are not caused by pathogens and cannot transmit from one person to another
• transmission of disease through air

  • when a person coughs/sneezes, numerous respiratory droplets containing pathogens are expelled
  • anyone within a close range will be infected (1 metre)
  • can be avoided via social distancing and wearing of mask
• transmission of disease through direct contact

  • spread through direct contact or by exchanging bodily fluids during sexual intercourse
  • STIs' such as HIV can be transmitted in this way
  • mothers with hepatitis B and syphilis can transmit these diseases to their child via breastfeeding as well
  • can be spread via blood of an infected person through a break through skin, as well as mucous membranes
• transmission of disease through contamination of food and water

  • can occur when food and water are not handled properly
  • can be prevented with hygienic food preparation , clean water supply , proper sewage treatment and good personal hygiene
• structure of a bacterial cell

  this

  A) cell wall

  B) cell membrane

  C) ribosome

  D) flagellum

  E) plasmid

  F) cytoplasm

  G) DNA

  
• structure of virus

  this

  A) protein coat

  B) genetic material

  
• influenza

  • respiratory disease caused by influenza virus
  • transmitted through droplets in the air or when a person touches a surface contaminated with the virus before touching their own mouth nose or eyes
  • symptoms include high fever, headache , stuffy nose , cough and sore throat
• reduce influenza transmission

  • get annual influenza vaccination
  • avoid coming close to people infected with influenza
  • if you are infected with influenza, cough or sneeze into a tissue and dispose of the tissue properly, or wear a surgical mask to prevent spreading the influenza to others
  • wash hands with soap and water properly if you have touched anything contaminated with influenza virus
  • avoid touching mouth eyes and nose
  • take antiviral drugs prescribed by doctor if unwell
• Pneumococcal disease

  • caused by the pneumococcus bacteria
  • transmitted through respiratory droplets
  • symptoms include fever, headache, vomiting, cough , chest pain and rapid breathing
• preventing pneumococcal disease

  • get the pneumococcal vaccination
  • do same preventive measures as influenza
  • take antibiotics prescribed by doctor to treat illness
• virus vs bacteria

  • bacteria can reproduce independently on their own but viruses need a living host
• structure of influenza virus

  this

  A) protein coat

  B) membrane envelope

  C) genetic material

  D) spike protein

  
• pathogens

  • germs that cause diseases (bacteria, virus etc.)
  • contains antigens that causes antibodies to be produced in our body
  • antibodies are the "frontline defence" of our immune system
• vaccines

  • when a pathogen enters our system , antibodies are able to recognise these specific antigens and fight them
  • however, when a new pathogen enters the body there may be no antibody to fight it
  • thus vaccines are agents that resemble pathogens and prevents infectious diseases by stimulating white blood cells to quickly produce antibody when the pathogen invades
  • "trains" the immune system to recognise this new pathogen
• how vaccines work

  • when a vaccine, containing an agent that resembles a pathogen, white blood cells are stimulated to produce antibodies, that are specific in action, and only destroy one type of pathogen
• underlying vaccination process

  1. white blood cell binds to agent
  2. WBCs are stimulated to divide
  3. WBCs produce antibodies
  4. antibodies destroy vaccine
  5. some of these WBC will remain in bloodstream, and will recognise the pathogens quickly in the future if they re-enter the bloodstream, and destroy them before they infect our cells

  
• antibiotics

  • drugs used against bacterial infections
  • ineffective against viruses
• how antibiotics work (I)

  1. Inhibits synthesis of bacterial cell wall ; cell walls are weakened and more water enters cell via osmosis, and cell expands and bursts and dies
  2. Inhibits synthesis of bacterial cell membrane ; cell membranes are weakened all cell is no longer protected as any substance can move into the cell
• how do antibiotics work (II)

  1. Inhibits synthesis of protein ; antibiotics bind to bacterial ribosomes, preventing synthesis of protein thus inhibiting growth
  2. Inhibits enzyme action in cytoplasm ; bacteria requires folic acid for growth, and antibodies inhibit enzyme needed for protein synthesis, hence inhibiting bacterial growth
• why antibiotics are ineffective on viruses

  • as mentioned earlier, antibodies act on cell membrane and wall , ribosomes and enzymes
  • since virus has none of those, antibodies are useless against them
  • one with a viral infection requires rest, and can take antiviral drugs
• why we should complete course of antibiotics

  f

  A) more

  B) less

  C) less

  
• antibiotic resistance


  • should a patient not complete their antibiotics course, the remaining bacterial cells will be less sensitive to the antibiotic, and will eventually be resistant to it
  • the antibody will not be able to kill off the respective bacteria anymore
  • can be reduced by not misusing or overusing antibiotics, and complete the course of it if necessary