What are the non-specific defence systems of the human body that protect it from pathogens?

A 'non-specific' defence system means that its response is the same for every invader (pathogen). In the human body this includes:

Skin- a physical barrier between the outside world and the inside of the body. The skin also produces secretions that are slightly acidic, which makes if hard for pathogens to grow.

Nose, trachea and bronchi- the hairs in the nose keep dust and larger micro-organisms out of the body. The dust and micro-organisms also stick to mucus produced by the inner lining of the respiratory tract (nose, trachea and bronchi), and these are then wafted away by cilia (tiny hairs) to prevent them from entering the lungs.

Stomach- the stomach contains hydrochloric acid which destroys micro-organisms- they are unable to survive in such an acidic environment.