Non-specific defence systems

The body is constantly defending against attacks from pathogens.

The first line of defence against infection stops the pathogens from entering the body. These first lines are general defences - they are not specific to fight against certain types of pathogen.

The skin:

  • is a physical barrier to infection
  • produces an oily secretion called sebum, which has antimicrobial properties

The respiratory system:

  • the lining of the respiratory system, including the nose, trachea and bronchi produce mucus, which traps foreign particles, including bacteria and viruses
  • tiny hair-like structures called cilia beat to remove mucus from the respiratory system

The stomach:

  • produces hydrochloric acid, which kills the majority of pathogens taken in through the mouth
A diagram of skin and its component parts such as nerve endings and fatty tissueA cross-section of skin