APPLIED RADIOLOGICAL ANATOMY

Detailed explanation-1: -The second line of defense is nonspecific resistance that destroys invaders in a generalized way without targeting specific individuals: Phagocytic cells ingest and destroy all microbes that pass into body tissues. For example macrophages are cells derived from monocytes (a type of white blood cell).

Detailed explanation-2: -The second line of defense are the non-specific phagocytes and other internal mechanisms that comprise innate immunity. The third line of defense are the specific lymphocytes that produce antibodies as part of the adaptive immune response.

Detailed explanation-3: -The second line of defense of the innate system includes chemical signals that produce inflammation and fever responses as well as mobilizing protective cells and other chemical defenses. The adaptive immune system mounts a highly specific response to substances and organisms that do not belong in the body.