Preventing Entry of Pathogens

• What are non-specific defences?

  • The body has a number of non specific defences against disease 
  • These are defences that work against all pathogens , to try and stop them from entering the body
• How does the skin try and stop pathogens from entering the body

  • The skin forms a protective layer covering the body 
  • The outer layer of the skin consists of dead cells and is difficult for pathogens to penetrate 
  • The skin also has sebaceous glands , which produce an oily substance called sebum which kills bacteria and fungi 
  • The skin can get damaged which allows pathogens to enter the body 
  • To stop this the skin scabs over

  
• Why do areas of the body that are not covered in skin need non-specific defences

  • Areas of the body that are not covered in skin (e.g. nose and mouth) present openings where pathogens can enter the body 
  • So these areas of the body have defence systems in place to protect us
• How does the nose try and prevent pathogens from entering the body

  • The nose contains hairs and mucus 
  • These can trap particles that contain pathogens before they enter the breathing system 
  • However sometimes pathogens path through the nose and then make their way down towards our lungs

  
• How do tears try and prevent pathogens from entering the body?

  There are enzymes in tears that destroy microorganisms

  
• How do the lungs try and prevent pathogens from entering the body?

  • The trachea and bronchi are covered with tiny hairs called cilia 
  • Cilia are covered in mucus which can trap pathogens 
  • The cilia now waft the mucus upwards towards the throat , where its swallowed into the stomach

  
• How does the stomach try and prevent pathogens from entering the body

  • There are lots of different pathogens that can be present on food 
  • To protect us, the stomach has glands in the stomach wall . which produce hydrochloric acid , which kills pathogens before they can make their way further down into the digestive system

  
• • Despite all the non-specific defences in the body , pathogens can still get into the human body and cause serious disease 
  • So to protect us , we also have the immune system