Human Defence Systems

• What are the components of the non-specific defence system in humans?

  1. Skin: Physical barrier and antimicrobial secretions
  2. Nose: Hairs and mucus to trap particles
  3. Trachea and bronchi: Mucus secretion and cilia action
  4. Stomach: Hydrochloric acid to kill pathogens
• What is the role of white blood cells in the specific immune system?

  They destroy pathogens that pass through the non-specific immune system
• What is phagocytosis?

  It is the process of engulfing and consuming pathogens
• How do antibodies help in the immune response?

  They bind to pathogens, clumping them together for easier identification by white blood cells
• What happens during a secondary infection with the same pathogen?

  Specific complementary antibodies are produced at a faster rate
• What is the primary function of the non-specific defence system?

  To prevent pathogens from entering the body
• What are the main components of the non-specific defence system?

  1. The skin

  • Acts as a physical barrier
  • Produces antimicrobial secretions
  • Skin flora competes with bad microorganisms

  1. The nose

  • Has hairs and mucus to prevent particles from entering lungs

  1. The trachea and bronchi

  • Secrete mucus to trap pathogens
  • Cilia waft mucus upwards to be swallowed

  1. The stomach

  • Produces hydrochloric acid to kill pathogens
• How does the skin contribute to the non-specific defence system?

  It acts as a physical barrier and produces antimicrobial secretions
• What role do good microorganisms play on the skin?

  They compete with bad microorganisms for space and nutrients
• What structures in the nose help prevent particles from entering the lungs?

  Hairs and mucus
• What is the function of mucus in the trachea and bronchi?

  To trap pathogens
• How do cilia in the trachea and bronchi assist in the defence system?

  They beat to waft mucus upwards so it can be swallowed
• What does the stomach produce to kill pathogens?

  Hydrochloric acid
• What is the role of the specific immune system?

  • Destroys pathogens that pass through the non-specific immune system
  • Involves white blood cells
  • Acts in three ways:

  1. Phagocytosis (engulfing pathogens)
  2. Producing antibodies
  3. Producing antitoxins
• What is phagocytosis?

  Engulfing and consuming pathogens
• How do antibodies protect the body?

  They bind to pathogens, clumping them together for easier identification by white blood cells
• What happens when antibodies bind to a pathogen?

  The pathogens start to clump together
• What occurs if a person is infected again with the same pathogen?

  Specific complementary antibodies are produced at a faster rate
• What does it mean to be immune to a pathogen?

  The individual will not feel the symptoms of the illness upon re-infection
• What do antitoxins do?

  They neutralize the toxins released by pathogens