ymphoid 1Immune2 System

Apuntes

ymphoid (Immune) System The lymphoid system is responsible for the immunological defense of the body. Some of its component organs—bone marrow, lymph nodes, thymus, and spleen—are surrounded by connective tissue capsules, whereas its other components, members of the diffuse lymphoid system, are not encapsulated. The cells of the lymphoid system protect the body against foreign macromolecules, viruses, bacteria, and other invasive microorganisms, and they kill cells of the self that were virally transformed. There are two categories of lymphoid organs: primary and secondary. Primary lymphoid organs (bone marrow and thymus) participate in the development of immunocompetent lymphocytes. Secondary lymphoid organs (lymph nodes, spleen, tonsils, and diffuse lymphoid tissue) function in trapping antigens and providing sites for the interactions of antigen-presenting cells (APCs) with immunocompetent lymphocytes, where they can mount an immune response and thereby remove the antigenic assault. Overview of the Immune System The immune system has two components: the innate immune system and the adaptive immune system. The first line of defense against invading pathogens is a physical barrie...