Explain the innate defense system

The body's defense system, also known as the immune system, functions to prevent any foreign antigen or pathogen from entering and causing harm to the body. The defense system can be of two types: innate or non-specific defense system, or acquired defense system.

Innate defense system functions to provide a non-specific defense to the body. It includes the body's natural barriers. The components of the innate defense system are:

• Physical barriers- Skin, hairs in the nasal cavity and ear, the cilia in the respiratory tracts, body hairs, and the mucus lining in the respiratory and the gastrointestinal passage serve as the components of physical barriers of the innate defense. The lacrimal gland secretions called tears, and the wax-like secretions from the sebaceous glands are also components of the innate physical barriers. 
• Chemical defense- These include the defense provided by the chemical mediators like chemokines, interleukins, and other cytokines that signal the neighboring cells about any pathogen invasion. The acid present in the stomach provides highly acidic conditions and resist pathogen survival.
• Immune cells- The lymphocytes, which are a component of the blood cells and include macrophages, neutrophils, natural killer cells, and dendritic cells, also function to fight against any pathogen. They function to phagocytose the pathogen and serve as a component of the body's innate defense