The Lymphatic System PDF

THE LYMPHATIC SYSTEM At the end of the session, the students should be able to:  state the major functions of the lymphatic system  describe the components of the lymphatic system  describe the organization of lymphatic vessels and the circulation of lymph  describe the structure...

THE LYMPHATIC SYSTEM At the end of the session, the students should be able to:  state the major functions of the lymphatic system  describe the components of the lymphatic system  describe the organization of lymphatic vessels and the circulation of lymph  describe the structure and functions of the lymphatic organs and tissue  The lymphatic system is a vascular network of tubules and ducts that collect, filter & return the lymph into blood circulation  Because it consists of organs that work together to perform certain function, it may treated as a separate system  The lymphatic system has a major role in the body’s defense against disease  Transport excess fluid from the interstitial space & return to the bloodstream  Lymph capillaries pick up the excess interstitial fluid & protein & return to the venous blood  Absorb lipids from digestive system & transport these substance to the venous circulation  Defense against invading microorganisms and disease in the lymph node  Lymph nodes & other lymphatic organ filter the lymph to remove microorganism  Lymphatic organ contain lymphocytes that destroy invading organisms Consists of:  Lymphatic capillaries  Lymphatic vessels  Lymphatic trunks  Lymphatic ducts  Lymphatic organs and tissues  Clear, colourless fluids that similar to blood plasma  Transport the plasma protein that seep out of the capillary beds back to blood stream  Carries larger particles such as bacteria & cell debris from damaged tissue to be filtered out & destroy by lymph nodes  Contain lymphocytes for defence mechanism  In the lacteal of small intestine, fats absorbed into the lymphatic – give the lymph milky appearance  Fluid that enters the lymph capillaries is called lymph  Returning the fluid into the blood stream prevents edema & help to maintain normal blood volume, plasma protein concentration & blood pressure  Begin as blind-ended lymph capillaries in tissue spaces  Found throughout the body except in epidermis, CNS, cornea of the eye & bones  The capillaries wall are more permeable to all interstitial fluids including protein & cell debris  Lacteal – lymphatic capillary that transport digested fats from the small intestine into blood  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Have one-way valves for lymph fluid to enter - Lymph prevent from backflow Opening Tissue fluid Valve  It is the lymphatic capillaries that merge to form a large vessels  Found along sides of arteries & veins serving the area  Functions - carry fluid away from the tissue spaces & return it to the venous system  Small lymphatics vessels will join to form a larger tributaries called lymphatic trunks  Lymphatic trunks will merge to become two large lymphatic ducts - right lymphatic duct & thoracic duct Right lymphatic duct  Carries lymph from the upper right side of the body (head & neck, right upper extremity & right side of thorax)  Empties into the right subclavian vein Thoracic Duct  The duct about 40cm long  Open into the left subclavian vein  Received lymph from the left side of the head, neck, and chest, the left upper extremity & the entire body below the ribs  Drains the lymph into venous blood via the left subclavian vein The flow of lymph are aided by;  Contraction of skeletal muscle - skeletal muscle contractions compresses lymphatic vessels to move the lymph  Respiratory pump - during inhalation, pressure higher in abdominal region caused lymph flow from abdomen to thoracic cavity  Contraction of smooth muscle in the larger lymphatic vessels – aid in the flow of lymph  Lymphatic vessel valves - prevent backflow of lymph Edema is an excessive accumulation of interstitial fluids in tissue spaces may due to:  Lymphatic system obstruction from infected lymph node or blocked lymphatic vessel,  Lack skeletal muscle contraction  Increased capillary blood pressure  Lymphatic Filariasis (Elephantiasis) is caused by filarial worms carried by mosquito whereby the adult worm live in the lymph nodes result in blockage the flow of lymph Consists of:  Thymus  Lymph nodes  Spleen  Tonsils  Bone marrow  Lies between the sternum and the heart  Contains large numbers of T cells, epithelial cell & macrophages  Functions - as the site of T cell maturation before enter into blood stream  Hormone thymosin – cause maturation of thymus & other lymphoid tissue  Shrinking of the gland begin in adolescence & with increasing of age, the effectiveness of T- lymphocytes respond to antigen declines  Large in the infant and will replaced with adipose & areolar connective tissue after puberty  T-lymphocyte - leave the thymus via blood & are carried to lymph nodes, the spleen & other lymphatic tissue & circulate in blood stream  Oval structure  Located along the lymphatic vessels  Contains lymphocytes & macrophages  About 600 lymph nodes available  Heavily concentrated near the mammary glands, axilla & groin  Lymph enters the lymph nodes through afferent lymphatic vessels, and exits through efferent lymphatic vessels  As many as 4-5 lymph afferent vessels may enter a lymph node & only one efferent vessels carries lymph away from the node Functions  Filtering & phagocytosis  Foreign substances filtered by the lymph nodes are trapped destroyed by macrophages through phagocytosis  Proliferation of lymphocytes  Place for activated T & B-lymphocytes to multiply  Antibodies produced by sensitized B- lymphocytes enter lymph & blood draining the node  If phagocytosis is incomplete – may stimulate inflammation & enlargement of node (lymphadenopathy)  Knowledge of the location of the lymph nodes and the direction of lymph flow is important in the diagnosis and prognosis of the spread of cancer by metastasis  There is an extensive network of lymphatic vessels associated with the breast Cancer cell from the breast can spread to the surrounding lymph nodes through these vessels Axillary nodes need to removed during surgical procedure of breast removal (mastectomy)  Hodgkin’s Lymphoma (Hodgkin’s Disease) is a cancer of the lymphatic system which spreads from lymph node to lymph node  It is the largest mass of lymphatic tissue in the body  Location - left hypochondriac region between the fundus of the stomach and the diaphragm Contain 2 types of tissue - white and red pulp White pulp  Consists mainly lymphocytes T lymphocytes - directly attack & destroy antigens in blood B lymphocytes - develop into antibody producing plasma cells, and the antibodies inactivate antigens in blood Red pulp  Consists of venous sinuses filled with blood & splenic cords consisting of RBCs, macrophages, lymphocytes, plasma cells, and granulocytes Functions  Phagocytosis – macrophages & lymphocytes remove worn-out or defective RBCs, WBCs & platelets  Lymphocytes in the spleen react to pathogen in the blood  Storage of blood - stores blood platelets in the red pulp up to 350ml  Immune response – contain T & B-lymphocytes which activated by the presence of antigen, e.g in infection  Erythropoiesis - production of blood cells during the second trimester of pregnancy  The spleen is often damaged in abdominal trauma. A splenectomy may be required to prevent excessive bleeding  It may removed due to disease  Lymphatic tissue that are not surrounded by a capsule  Contain B & T-lymphocytes that migrated from bone marrow & thymus  Important for early detection of invaders  No efferent lymphatic vessels, so did not filter the lymph  Main groups – tonsils & lymphoid follicles  Peyer’s patches are found in the ileum of the small intestine Tonsils  Lymphatic nodules that embedded in a mucous membrane at the junction of the oral cavity and the pharynx  5 Tonsils ( pharyngeal (adenoids), 2 palatine tonsil & 2 lingual tonsils)  Function - to protect against invasion of foreign substances around nasal & oral cavities Adenoidectomy  It is surgical removal of pharyngeal tonsil  Adenoids, also known as pharyngeal tonsil. They protect the body from harmful bacteria and viruses  If the bacterial invasion is aggressive enough, the adenoids themselves can become infected  It is a soft, flexible tissue inside the bone  Responsible for the production of blood cells: RBC, WBC & platelets  Bone marrow stem cells play an important role in immunity as they generates lymphocytes  Certain white blood cells mature in bone marrow  The functions of the lymphatic system are:  Return excess interstitial fluid to the blood  Absorption of fats & fats-soluble vitamins from digestive system  Defense against invading microorganisms and disease  Thoracic duct received lymph from the entire body except the upper right side of the body  Right lymphatic duct will drains lymph into venous blood via right subclavian vein  Upper right side of the body will drained the lymph to the right lymphatic duct  The flow of the lymph are assisted by the:  Skeletal pump  Respiratory pump  Contraction of smooth muscle of lymphatic vessels  Lymphatic vessel valves  The purpose of lymph to flow through lymph nodes are to  Filter lymph  Remove foreign substance through filtering, phagocytosis & immune reaction  Edema is the complication if there is an obstruction to lymphatic vessels  Tonsils is the large lymphatic tissue in a mucous membrane of the mouth and throat  Spleen is the largest lymphatic organ in the body  Bleeding is the complication when the is an injury to the spleen  Lymphatic vessel valve prevent backflow of lymph within the vessels