Inflammatory barriers is a type of Innate Immunity. Tissue damage and infection induce leakage of vascular fluid, containing chemotactic signals like serotonin, histamine and prostaglandins.

Interferons are a group of signalling proteins produced by virus infected cells. They interfere with viral replication and hence named interferons. A virus infected cell releases interferons which induce antiviral state in the uninfected cells. They are chemical mediators under physiological barriers offering Innate immunity.

The type of barrier that involves macrophages are the
(i) Phagocytic barriers which is a type of innate immunity.
(ii) In this mechanism, specialised cells such as monocytes, Neutrophils and tissue macro phages pha cytose and digest whole microorganisms.

The immune responses may be primary or secondary.
(i) The primary immune response occurs when a pathogen comes in contact with the immune system for the first time.
(ii) The secondary immune response occurs when a person is exposed to the same antigen again. During this time, immunological memory has been established and the immune system can start producing antibodies immediately. Within hours after recognition of the antigen, a new army of plasma cells are generated. Within 2 to 3 days, the antibody concentration in the blood rises steeply to reach much higher level than primary response. This is also called as "booster response".

Lysozyme present in saliva acts as an antibacterial agent and cleaves the bacterial cell wall.

(i) Primary Lymphoid organ: Thymus is a primary lymphoid organ.
Function: One of its main secretions is the hormone thymosin. It stimulates the T cell to become mature and immunocompetent.
(ii) Secondary Lymphoid organ: Tonsils is a secondary lymphoid organ.
The tonsils are part of the lymphatic system, which help to fight infections. They stop invading germs including bacteria and viruses.