Non-specific defense systems

• What is the job of the non-specific defense system?

  To prevent pathogens from entering the body.
• What is skin and how does it stop pathogens entering the body?

  The skin forms a protective layer covering the body. The outer layer consists of dead cells and it difficult for pathogens to penetrate. The skin also produces an oily substance called sebum which kills bacteria. Sometimes the skin is damaged and can allow pathogens to enter the body, to stop this the skin scabs over.
• How does the nose stop pathogens entering the body?

  The nose contains hairs and mucus, these can trap pathogens before they enter the breathing system. However, some pathogens pass through the hairs and mucus which travel towards the lungs so the trachea an bronchi are covered in tiny hairs called cilia which are covered in mucus to trap pathogens. The cilia now waft the mucus upwards towards the throat where it is swallowed into the stomach.
• How does the stomach defend us against pathogens?

  The stomach contains hydrochloric acid, this kills pathogens before they make their way further down the digestive system.