Immunity

Lymphocytes

Cytoxic T-cells

attack foreign cells or body cells infected by viruses

B-cells

differentiate into plasma cells which produce antibodies

Natural Killer (NK) cells

attack foreign cells, normal cells infected with viruses, or cancer cells appearing in normal tissue

Lymphatic tissues and organs

connective tissues dominated by lymphocytes

Lymph nodes - contain macrophages and lymphocytes acting on lymph

Thymus - site for maturation of T-cells

Spleen - contains macrophages and lymphocytes acting on blood

Nonspecific defenses

Macrophages

• tissue phagocytes derived from monocytes
• phagocytize cellualr debris, pathogens and antibody bound pathogens

Specific defenses (Immunity)

Cellular immunity

direct attack by cytotoxic T-cells

Humoral immunity

attack by circulating antibodies

Antibodies bind to antigen and

• prevent pathogen attachment
• precipitate immune complexes
• enhance phagocytosis

Functions of the lymphatic system

• There is a continual movement of fluid from the capillaries, into the interstitial spaces between tissue cells, and back to the circulation via the lymphatic vessels.
• Return of lost plasma from the capillaries
• Collect, capture and destroy pathogens in the body

Lymphatic vessels

Lymphatic capillaries

Lymphatics ducts

ducts empty into the venous system at the junction of the internal jugular vein and and the subclavian vein on the corresponding side

© David G. Ward, Ph.D.  Last modified by wardd 23 May, 2006