Lines of Defence

• 1st:

  • Skin - physical barrier against pathogens
  • Fluids - tears & saliva that wash away dirt and dust
  • Nasal hairs - filters dust and dirt in the nose and throat
  • Mucus - Lines the throat and nose to trap particles
  • Urine flow - flushes pathogens out of the bladder and the urethra
• 2nd:

  Fever

  • The core body temperature increases above 38 degrees to slow down and kill pathogens
  • This is done considering pathogens thrive in moderate temperatures

  Inflammation

  • Swelling and redness on the area of infection.
  • This allows for more blood flow with white blood cells that will kill of pathogens

  Phagocytes

  • White blood cells that protect the body by "swallowing" or engulfing pathogens that they do not recognise
• 3rd - Pt.1:

  • Lymph is filtered in the lympth nodes. Trapped pathogens are consumed by macrophages
  • The spleen removes pathogens and foreign proteins from the lymph fluid.
  • The lymphatic system carries lymphocytes and macrophages that destroy foreign proteins and manufacture antibodies.
• 3rd - Pt. 2:

  • When a person is sick, B cells (white blood cells) recognise the pathogen and produce antibodies (proteins) on its cell membrane. Antibodies connect to markers on the pathogen to identify them.
  • Each pathogen has unique markers and only connect with antibodies that have a similar shape.
• 3rd - Pt.3:

  • The B cell releases millions of antibodies into the blood to fight off the pathogen. The B cell clones itself into an army, releasing more antibodies to fight and neutralise the pathogen.
  • The memory of the pathogen is remembered by remaining B cells that act as memory cells. This allows for a stronger and quicker response to the pathogen if one is infected by the same one. This is known as immunity.
• Macrophages - white blood cells that surround and kill microorganisms.
• Lymphocytes - Immune cells produced in the bone marrow that help fight cancer and foreign blood cells in the immune system along with producing anti-bodies.
• Lymph - watery fluid in the lymphatic system that carries nutrients and proteins to cell & tissue.