Lymphatic System

3 parts of Lymph System Vessels- a network of lymph tissues begins in peripheral tissues and ends at connections to the venous system Fluid- a fluid called lymph flows in lymphantic system. This contains plasma but at a lower protein level. Lymphoid organs- contains large number of lymphocytes found in spleen, nodes thymus

Functions of the lymph system 1. The production, maintenance, and distribution of lymphocytes. 2. The return of fluids and solutes from peripheral tissues to the blood. 3. The distribution of hormones, nutrients and waste products from tissues of origin to the general circulation.

Vessels Start as lymphatic capillaries, then veins, then through valves to the thoracic duct and right lymphatic duct.

Lymph organs Lymph nodes are small oval organs ranging in diameter from 1 mm to 1 inch. Usually filters the lymph before it reaches the veins. Usually 99% is removed and you get T cell and B cell responses to antigens.

Thymus Located behind the sternum, weighs between grams, two lobes called lobules and septae which is then divided into cortex and medulla These house the mature T cells.

Spleen Contains the largest amount of lymphatic tissue, it is 12 cm long and can weigh 160 g. It has red pulp and white pulp. Helps with immune response.

Types of defense Nonspecific defense- include physical barriers, phagocytic cells, immunological surveillance, interferon, complement, inflammation and fever Specific defense aka specific resistance or immunity.

Forms of immunity Specific resistance immunity- responds to threats on an individualized basis Acquired immunity- produced by prior exposure or antibody producion Innate immunity- genetically determined no prior exposure or antibody production involved.

Properties of immunity Specificity Versatility Memory Tolerance

Types of T cells Cytotoxic t cells ( 3ways) page Memory t cells Suppressor T cells Helper T cells

B cells and antibodies B cells start by having helper T cells Therefore get following 4 functions (page 424)

Antibody functions 1. Neutralization 2. Agglutination and precipitation 3. Activation of complement 4. Activation of phagocytes 5. Enhancement of phagocytosis 6. stimulation of inflammation

Forms of immunity Active immunity-produced by antibodies that develop in response to antigens Passive immunity-produced by transfer of antibodies from another person

Classes of antibodies