Fighting Disease

• How does the skin defend against disease?


  It acts as a barrier to pathogens and also secretes antimicrobial substances to kill pathogens
• How does your nose defend against pathogens?


  Hair and mucus trap particles which could contain pathogens
• How do your lungs help defend against pathogens?

  • The trachea and bronchi secrete mucus to trap pathogens
  • The trachea and bronchi are lined with cilia which waft the mucus up to the back of the throat to be swallowed
• How does the stomach help defend against pathogens?

  Stomach acid kills pathogens
• Which organ system is responsible for fighting infection?

  The immune system
• Which part of the immune system travels around the body in the blood?

  White blood cells
• What are the two methods white blood cells use to fight pathogens?

  • Engulfing them
  • Producing antibodies and antitoxins
• What is the term for when white blood cells engulf and digest pathogens?

  Phagocytosis
• What is an antigen?

  A molecule on the surface of a pathogen which is unique to each type
• What type of molecule are antibodies?

  Proteins
• What do antibodies do?


  Lock onto invading pathogens to be found and destroyed by other white blood cells
• When do antibodies begin to be produced?


  When a white blood cell comes across a foreign antigen
• How many types of antigen can each antibody lock on to?

  One type
• What happens after antibodies are produced to lock onto the foreign antigen?

  They are produced rapidly and transported around the body to find other similar antigens
• What happens when a person is infected with a pathogen they have fought off before?


  The white blood cell starts to rapidly produce the antibodies to kill it
• What are antitoxins?


  Substances that counteract toxins produced by bacteria