LYMPHATIC SYSTEM

• As 'Middle man' of circulation it mediates exchange between blood and the tissue. It is also a collecting system like venous system.
• Basically 'open type' circulation but also consists of thin walled lymphatic channels and lymphatic capillaries at some places.
• Through out the body it is interwoven with blood vascular system except in the brain, spinal cord, cornea of eye and epidermis of skin.
• 4% of plasma protein filter out into tissue fluid per hour and is returned to blood only by the lymphatic system.
• Consists of lymph sinuses, lymphatic channels, lymph hearts, and lymph nodes with lymph.
• A general defect of defense system due to the malfunctioning or disorders of lymphatic organs is called Hodgkins disease.
• Lymph is the fluid which enters lymphatic capillaries from the tissue, it constitutes 25% of total body weight.
• Contains all the essential Gomponents of blood except RBC and some large protein molecules, which cannot filter out through endothelial wall.
• It is the part of tissue fluid which in turn, is the part of plasma. It stores gases, water, salts and waste products.
• Baird Hastings called lymph as the "sea within us".
• Lymphatic Channels are non contractile thin-walled structures with numerous valves to prevent back flow of lymph.
• In mammals all these channels finally lead to the thoracic duct (left and right) which posteriorly dilates as cisterna chyli and anteriorly opens into sub-clavian veins.
• In intestinal villi is called as lacteals and in spleen called as cords of BiIlroth.
• Aggregated lymphatic tissue forms node-like structures in certain parts of the body mainly at joints, and thoracic and abdominal walls for the formation of W.B.C.
• Lymph nodes are the compact aggregated mass of lymphoid tissue abundant in mammals, act as 'biological filter' to remove foreign bodies and worm out cells from body parts.
• Called as Peyer's patches in intestinal wall and tonsils in pharyngeal wall.
• Their larger versions are called as lymph organs/glands e.g. spleen, thymus etc.