There are three main ways in which the body may prevent infection and fight off invading pathogens, these are barriers, humoral components and cell responses.
Barriers refer to the surfaces of the body that are in contact with the environment. In the main it refers to epithelial surfaces such as the skin, the intestine and the respiratory tract.
Humoral components refer to molecules secreted by cells, examples include lysozyme, complement components, cytokines and antibodies.
Cell responses include the roles played by phagocytes, natural killer cells, dendritic cells, T cells (helper, cytotoxic, memory) and B cells.
The two main types of immunity are innate and adaptive. Innate immunity refers to general mechanisms of fighting off invading pathogens, while adaptive immunity refers to the bodies ability to augment its immune respose to particular pathogens when they are exposed to them. Innate immunity is often termed non-specific immunity and adaptive immunity is often termed specific immunity.
Non-specific
Specific
Innate and adaptive immunity differ in the three main arms of immunity, barriers, humoral components and cell responses. It must be noted that both innate and adaptive immunity respond together in a coordinted fashion to fight off pathogens, distinction between them in mainly useful in describing the immune reponse,