immune system

The immune system is an important system for the body to perform immune responses and immune functions. The immune system consists of immune organs and tissues, immune cells (such as hematopoietic stem cells, lymphocytes, antigen-presenting cells, granulocytes, mast cells, red blood cells, etc.)   and immune molecules (such as immunoglobulins, complements, various cytokines and membrane molecules Etc) composition.

Immune tissue is also called lymphoid tissue. Immune tissues are widely distributed in humans and animals. The intestine, respiratory tract, urogenital tract and other mucous membranes contain a large number of non-enveloped diffuse lymphoid tissues and lymphoid nodules. Plays a major role in infection immunity.

Lymphoid tissue is the main component of enveloped lymphoid organs such as the thymus, spleen, and lymph nodes. Lymphatic organs are also called immune organs because of their immune function.

Immune organs can be divided into central immune organs and peripheral immune organs according to their occurrence and function. The two are interconnected through blood circulation and lymph circulation. Central immune organs occur earlier and are composed of bone marrow and thymus. Pluripotent hematopoietic stem cells develop into mature immune cells in the central immune organs and are transported to peripheral immune organs through blood circulation. Peripheral immune organs occur relatively late and are composed of lymph nodes, spleen, and mucosa-associated lymphoid tissues. Mature immune cells settle in   these   areas   and generate immune responses after receiving antigen stimulation.

Lymphocytes and monocytes flow in and out of peripheral immune organs and tissues through blood circulation and lymph circulation, forming a complete network of the immune system, which can not only mobilize immune cells in time to cause them to aggregate on the surface of the body and pathogens such as pathogens in various organs, but also The antigens at these sites can be taken up by the antigen presenting cells and carried to the corresponding peripheral immune organs or tissues, thereby activating T cells and B cells, thereby exerting an adaptive immune response and effect.