Immune System & Defences

• What act as barriers to reduce the entry of pathogens?

  Enzymes in tears

  Hairs in the nose

  Skin
• How does skin help to defend against disease?

  It secretes oils and antimicrobial substances that kill pathogens

  It covers the body, physically preventing pathogens from entering
• Does skin act as a physical or chemical barrier to pathogens?

  physical
• The nose has hairs inside it that act as a physical barrier to pathogens. What are the hairs in the nose coated with to catch pathogens?

  mucus
• The cells that line the trachea, bronchi and bronchioles have tiny hair-like projections that waft the mucus and pathogens away from the lungs. 

  What are these structures called? 

  cilia
• What substance does the stomach produce to kill pathogens? 

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

  To locate and destroy pathogens that enter the body
• Which type of cells are part of the immune system?

  white blood cells
• What are functions of white blood cells?

  Produce antitoxins 

  Producing antibodies 

  Phagocytosis 
• 1. Phagocytosis is carried out by a special type of white blood cell called a what ? 

  phagocyte.
• 1. The first step is for the phagocyte to track down a pathogen, and then bind to it. 
• 1. The phagocyte's membrane will then surround the pathogen and engulf it.
• What do antitoxins do?

  Bind and neutralise the toxins produced by bacteria