Living World

• Immune system


  A network of cells, tissues, organs, and the substances they make that helps the body fight infections and other diseases
• Purpose of the immune system


  • Protect the body from infection, recognise 'invaders' such as bacteria, viruses and fungi and abnormal cells like cancer cells, create an immune response and help the body fight the invasion
• 1st Line of Defence


  Skin and Hair (Physical Barriers)
• 2nd Line of Defence


  White blood cells
• 3rd Line of Defence


  Memory cells, B and T cells
• Problems


  • Allergies
  • Asthma
  • Autoimmune diseases
• Systems


  • Skeletal
  • Muscular
  • Nervous
  • Endocrine
  • Cardiovascular
  • Lymphatic
  • Respiratory
  • Digestive
  • Urinary
  • Reproductive
• Organs involved in the immune system


  • Lymph nodes
  • Lymph vessels
  • Skin
  • Sweat Glands
  • Digestive track
  • Nose and trachea
• Cell

  Smallest living part of an organism
• Tissue

  Collection of specialised cells
• Organ

  A group of tissues in a living organism that have been adapted to perform a specific function
• System

  Collection of organs
• Organism

  Collection of systems
• The skin

  • A physical barrier that prevents the entry of pathogens
• Nose hair

  • Filter air entering your respiratory tract
• Mucus

  • Traps germs
• Digestive Juice

  • Enzymes kill germs and break down carbohydrates, fats, and proteins
• 1st Line of Defence


  1. Physical Barriers: Skin blocks germs from entering the body, Clots form to close gaps in this defence

  2. Cilia (fine hairs): Nasal passage, Trachea, Outer ear all filter dust and bacteria from the air

  3. Mucus: Dust and pathogens stick to it, coughing and sneezing expel them

  4. Chemical Barriers: Sweat and Tears dehydrates germs due to its high salt content
• 2nd Line of Defence


  White blood cells travel through the body and detect enzymes given off by pathogens, They stick to the blood vessel and give off chemicals that attract more white blood cells, Then enter the infected tissue and absorb bacteria through phagocytosis
• 3rd Line of Defence


  Destroys pathogens so quickly without producing symptoms, Uses pieces of dead pathogen (antigen) to program attack cells such as T cells, B-cells absorb that antigen and produce antibodies that destroy pathogens
• Cells

  • Our body has chemical markers that are unique, If something enters your body without the markers, that body destroys it. E.g transplants
• Virus

  An organism that hijacks host cells and forces them to make more viruses, Do this by injecting their DNA into our own or injecting genetic material that the body transforms into proteins and makes them a new virus
• Viruses

  • HIV (from AIDS)
  • Covid-19
  • Flu
  • Small pox
  • Ebola
• Bacteria

  Microscopic single called an organism that reproduces with binary fusion. They attack hosts for nutrients.
• Diseases of note


  • Botulism
  • Tetanus
  • Anthrax
• The immune system fights disease
• Medicine used to fight disease


  • Preventative medicine: Vaccines, Healthy lifestyle, Body Screening
  • Treatment: Chemotherapy, Radiation therapy, Pharmacotherapy
• Ways to prevent infection


  • Good hygiene
  • Vaccine
  • Sanitation
  • Quarantine
• Food preservation methods


  • Refrigeration
  • Preservatives
  • Sugar
  • Tin cans
• Antibiotics


  Chemicals produced initially by mould to kill bacteria. Discovered 1929 by Alexander Flemming.
• Causes of antibiotic resistance


  • People not finishing the script
  • Using human medication on livestock
  • Over prescription by doctors
• Ways to minimise antibiotic resistance


  • Prescribing medicines only for as long as needed
  • Educate people to follow the script
  • Keep reserve antibiotics that are only used as a last resort
• Immunity


  Protection against an infectious disease
• Vaccine

  A preparation that stimulates the body's immune response to diseases
• Antibodies


  Proteins that protect you from unwanted substances that enter your body
• Penicillin


  Works by breaking down the bacterial cell walls
• T cells


  Protect you by destroying harmful pathogens and sending signals to control your immune system response