LYMPHATIC SYSTEM

The Lymphatic System  Cleaning system of the body  Drains all extra fluid from the tissues  Closely associated with the vascular system  Looks like veins with thin walls and valves  Contains:  Capillaries  Nodes  Vessels

Functions  Protects against foreign materials  Bacteria  Viruses  Fungi  Protozoa  pathogens  Absorbtion of fats  Lymphatic vessels called lacteals transport fats to the circulatory system

Lymphatic System Composition  Lymph  Vessels  Nodes and glands  Nodules  Spleen  Thymus gland

Lymph Fluid  Straw colored  Similar to plasma  Functions:  Maintains blood volume and blood pressure by returning tissue fluid to blood  Returns small proteins to blood  Moves by:  Same mechanism facilitating venous blood return to the heart  Contractions of vessels between valves

Lymph Vessels  Found close to veins  Superficial  deep  Structure similar to veins  Thin-walled – 1 layer endothelium  Contain valves  More permeable  Carry lymph into and out of lymph nodes and finally back to the vascular system  One way system – flowing toward the heart  Named according to location

Lymph Vessels NOT located in the:  Cuticles  Hair  CNS  Eyeball  Bone marrow  Spleen  Nails  Epidermis  Cartilage  Inner ear

Lymph Vessels - Capillaries  Begin as dead end capillaries in the tissue  Very permeable  Collect tissue, fluid and protein  Specialized:  Lacteals – transfer fatty acids and vitamin A  Found in intestines

Order of Flow  Lymphatic vessels join to form lymphatic trunks  Lymphatic trunks join to form :  Thoracic duct (3/4 of body) aka – left lymphatic duct  Right lymphatic duct (drains right arm, and right side of head, neck and upper torso  These empty into subclavian veins at junction with internal jugular vein  Capillaries merge to form larger lymph vessels which flow into regional nodes  Lymph vessels carry lymph away from regional nodes to right or left lymphatic ducts

Right Lymphatic Duct  Receives lymph from upper right quadrant of the body  Empties into right subclavian vein  Opening into vein contains semilunar valves that prevent blood back flow

Left Lymphatic Duct (thoracic duct)  Receives lymph from all parts of body except the upper right head, neck and chest  Larger of the two ducts  Temporary storage area – cysterna chyli

Flow chart  Lymphatic capillary  Lymphatic vessel  Lymph node  filtered  Lymphatic vessel  Lymphatic trunk  Collecting duct  Before the heart – cysterna chyli  Subclavian vein  Returns through cardiovascular system

Lymph Nodes and Nodules  Small lymphatic tissue masses located along lymph vessels  Lymph is filtered here  Found in clusters  Waste-water treatment plants  Vary in size  Centers for lymphocyte production – what does this do?  Primary groupings – cervical, axillary, and inguinal  Site of cancer growth  Lymph nodule DO NOT Filter fluid

Node and Nodules cont….  Structure:  Fibrous connective tissue capsule with partitions  Inside lymphocytes and macrophages  Main groups:  Cervical  Axillary  Tracheobronchial  Mesenteric  Inguinal Inflammation of lymph nodes - BUBOS

Lymph Movement  If flow of lymph is interrupted – edema results  Sometimes surgery can cause this because they are removed or disturbed  Lymph nodules  Do not filter fluid  Found beneath moist epithelium of mucous membrane  Digestive system  Respiratory system  Urinary system

Mucosa Associated Lymphoid Tissue  MALT  Lymph nodules are also found singly or in groups  Peyer’s patches in ileum  Tonsils  Some in appendix

Lymphatic Organs  Primary Organs  Red bone marrow  Thymus  Lymph nodes  Secondary Organs  Lymph nodules  Spleen

Tonsils  Act as a filter against disease  Palatine  Bilaterally soft palate  Pharyngeal  Located on the posterior wall of the upper pharynx  Lingual  Located posterior portion of the tongue

Thymus  Located:  Upper thorax, in mediastinum above heart  Most activity during fetal and prepubescent period  Larges at age then atrophies  Most thymus material replaced by fat and connective tissue  Produces hormone thymosin  Matures T-lymphocytes  Promotes growth/activity of lymphocytes throughout the body

Spleen  Largest lymphoid organ  Upper left quadrant  Protected by rib cage

Functions of spleen  Blood formation  All blood cells in fetus  Only lymphocytes and monocytes after birth  Blood filtration  Removes bacteria, particles, worn out RBC’s and platelets  Blood storage  Can contain over one pint of blood  If the spleen is damaged it is removed and you will suffer from a weakened immune system – not considered a vital organ

Reticuloendothelial system  System of cells that:  Destroy old blood cells  Foreign substances  Cancer cells  Cells are found in:  Liver  Spleen  Bone marrow  Lymph nodes  brain

Disorders of the lymphatic system  Lymphangitis  Septicemia  Lymphadenitis  Lymphedema  Elephantiasis  Lymphadenopathy  Mononucleosis  Splenomegaly  Lymphoma  Hodgkins  Non – Hodgkin’s lymphoma