Glossary: The Immune System


adaptive immune response relatively slow but very specific and effective immune response controlled by lymphocytes

afferent lymphatic vessels lead into a lymph node

antibody antigen-specific protein secreted by plasma cells; immunoglobulin

antigen molecule recognized by the receptors of B and T lymphocytes

barrier defenses antipathogen defenses deriving from a barrier that physically prevents pathogens from entering the body to establish an infection

B cells lymphocytes that act by differentiating into an antibody-secreting plasma cell

bone marrow tissue found inside bones; the site of all blood cell differentiation and maturation of B lymphocytes

bronchus-associated lymphoid tissue (BALT) lymphoid nodule associated with the respiratory tract

chyle lipid-rich lymph inside the lymphatic capillaries of the small intestine

cisterna chyli bag-like vessel that forms the beginning of the thoracic duct

efferent lymphatic vessels lead out of a lymph node

germinal centers clusters of rapidly proliferating B cells found in secondary lymphoid tissues

high endothelial venules vessels containing unique endothelial cells specialized to allow migration of lymphocytes from the blood to the lymph node

immune system series of barriers, cells, and soluble mediators that combine to response to infections of the body with pathogenic organisms

innate immune response rapid but relatively nonspecific immune response

lymph fluid contained within the lymphatic system

lymph node one of the bean-shaped organs found associated with the lymphatic vessels

lymphatic capillaries smallest of the lymphatic vessels and the origin of lymph flow

lymphatic system network of lymphatic vessels, lymph nodes, and ducts that carries lymph from the tissues and back to the bloodstream.

lymphatic trunks large lymphatics that collect lymph from smaller lymphatic vessels and empties into the blood via lymphatic ducts

lymphocytes white blood cells characterized by a large nucleus and small rim of cytoplasm

lymphoid nodules unencapsulated patches of lymphoid tissue found throughout the body

mucosa-associated lymphoid tissue (MALT) lymphoid nodule associated with the mucosa

naïve lymphocyte mature B or T cell that has not yet encountered antigen for the first time

natural killer cell (NK) cytotoxic lymphocyte of innate immune response

plasma cell differentiated B cell that is actively secreting antibody

primary lymphoid organ site where lymphocytes mature and proliferate; red bone marrow and thymus gland

right lymphatic duct drains lymph fluid from the upper right side of body into the right subclavian vein

secondary lymphoid organs sites where lymphocytes mount adaptive immune responses; examples include lymph nodes and spleen

spleen secondary lymphoid organ that filters pathogens from the blood (white pulp) and removes degenerating or damaged blood cells (red pulp)

T cell lymphocyte that acts by secreting molecules that regulate the immune system or by causing the destruction of foreign cells, viruses, and cancer cells

thoracic duct large duct that drains lymph from the lower limbs, left thorax, left upper limb, and the left side of the head

thymocyte immature T cell found in the thymus

thymus primary lymphoid organ; where T lymphocytes proliferate and mature

tonsils lymphoid nodules associated with the nasopharynx