The Lymphatic System

What is the Lymphatic System System working closely with circulatory system Excess or unwanted tissue fluid is returned to the bloodstream

Functions Lymphatic System Drains excess fluid Transports fats and fat soluble vitamins from the digestive tract through the “Lacteals” into the blood Plays a vital role in immune system Digestive - lymphatic vessels in small intestines help with the absorption of fats during digestion - they are then transported around the body in the circulatory system and distributed by cells to be used as energy Muscular - lactic acid formed from exercising muscles or from tension in muscles are drained away in lymphatic system

Structure of Lymphatic System Lymphatic capillaries Lymphatic vessels Lymphatic nodes Lymphatic ducts Spleen Tonsils Thymus Bone marrow

What is Lymph Fluid similar to blood plasma Excess or unwanted tissue fluid Lympha = clear water

Formation and Flow of Lymph Plasma freely moves through the capillary wall to form interstitial fluid More fluid travels from the blood capillary wall than returns because the pressure inside the capillaries is too high The excess fluid (approx. 3 litres) per day drains into lymphatic capillaries and becomes lymph Most plasma proteins are too large to leave blood vessels So interstitial fluid contains only a small amount of protein Any protein that does escape cannot return to blood by diffusion - high levels inside low levels outside prevent this Important function of lymphatic vessels is to return leaked plasma proteins to the blood

Lymph circulation Valves ensure one way movement Muscles - a milking action caused by muscle contraction Respiratory pump - pressure changes during inhalation causes lymph to flow from abdominal region to thoracic region Suction - negative pressure helps pull lymph upwards into lymphatic ducts

Sequence of Flow of Lymph Arteries (blood) Blood Capillaries (blood) Tissue and Cells (interstitial fluid) Lymphatic Capillaries (lymph) Lymphatic Ducts (lymph) Subclavian Veins (blood)

What are Lymphatic Capillaries Lymph capillaries are found throughout the body Slightly larger than blood capillaries Single layer of Endothelial Cells which overlap - when pressure is greater in interstitial fluid - the cells separate slightly and fluid enters the capillary Avascular - without blood vessels - the vessels located in the adjacent connective tissue that supply nutrients and remove waste Endothelium - layer of simple squamous epithelium - lines cavities of heart blood vessels and lymphatic vessels

Lymphatic Capillaries

Lymphatic Vessels Lymphatic Capillaries unite to form larger Lymphatic Vessels Resembling veins in structure thinner walls and more valves Function Collect lymph from lymphatic capillaries and convey towards the heart In the intestine the lymphatic vessels are called Lacteals Digestive - lymphatic vessels in small intestines help with the absorption of fats during digestion - they are then transported around the body in the circulatory system and distributed by cells to be used as energy In the skin lymphatic vessels lie in subcutaneous tissue (between dermis of skin and deep fascia of the muscles) and generally follow veins

Lymph Nodes Location - scattered throughout the body in groups and typically arranged in two sets superficial and deep Size varies from pin head to an almond Structure - made of lymphatic tissue - surrounded by tough fibrous tissue and supported by strands of fibrous tissue called Trabeculae Afferent vessel transports lymph to node Efferent vessel transports from the node

Lymph Nodes of the Head Anterior Auricular Nodes Posterior Auricular Nodes Submandibular Nodes Occipital Nodes Cervical Nodes

Key Lymph Nodes Submandibular Nodes Superficial and Deep Cervical Nodes Anterior / Posterior Auricular Nodes Occipital Nodes Axillary Nodes Supratrochlear Nodes Inguinal Nodes Popliteal Nodes

Functions of Lymph Nodes Filters harmful cells and dead tissue Destroys harmful material Produce new lymphocytes (white blood cells) Produces antibodies against particular infections

Lymphatic Tissue Key part of immune system Contains many cells Phagocytes - engulf and destroy harmful waste and bacteria Cells producing antibodies and cells dividing to produce new lymphocytes Areas of body containing lymph tissue include: Lymph nodes, spleen, tonsils, Bone marrow, thymus gland Peyers patches, appendix Payers patches - located in small intestine - prevent bacteria from entering the blood stream Thymus Gland - between the lungs - Immature T Cells mature in the Thymus Gland - using Thymic Hormones - is large in an infant and after puberty fat and connective tissue replace much of the thymic tissue - after maturity the gland has atrophied 2 main types of lymphocytes - B Cell Lymphocytes - responsible for producing Antibodies T Cell Lymphocytes - various roles in immune system including destroying foreign substances

Lymphatic Ducts Lymphatic vessels join to form Lymphatic Ducts All lymph passes into two main lymphatic ducts: The Right Lymphatic Duct The Thoracic Duct Right Lymphatic Duct right side of head, chest and neck and right arm, into right Subclavian Vein Thoracic Duct the left side of the head, the neck, both legs, left side of trunk and left arm, into the Subclavian Vein Thoracic Duct- 40cm long extending from second vertebra to the root of neck Right Lymphatic Duct - 1.5cm long positioned at root of the neck

Routes for drainage of lymph into Thoracic Duct and Right Lymphatic Duct

The Spleen Structure - largest mass of lymphatic tissue, outer capsule of fibrous tissue with trabeculae & pulp mass. Location - located upper left of the abdomen Functions; Forms new lymphocytes Destroys worn out thrombocytes and erythrocytes Blood reservoir in case of haemorrhage and shock Helps fight infection Spleen - is about 12cm in length Does not filter lymph - no afferent or efferent vessels Ruptured Spleen - organ most often damaged in cases of abdominal trauma - Removal of Spleen called a Splenectomy - prevents patient bleeding to death - function taken over by Liver and Bone Marrow

Non-Hodgkin’s Lymphoma Hodgkin’s Disease Non-Hodgkin’s Lymphoma Cancer of the lymphatic Tissue (Epstein Barr virus) Usually arising in lymph nodes (15 to 35) Painless enlargement of one or more lymph nodes Fatigue Weight loss Treatment Radiotherapy Chemotherapy Bone marrow transplant Hodgkin’s Disease is curable Cancer of the lymphoid tissue, which includes the lymph nodes, spleen, and other organs of the immune system (over 60’s)

Hashimoto’s Thyroiditis Lymphoma Lymphoma - a cancer that begins in the lymphocytes of the immune system An autoimmune disease where the body's own T-cells attack the cells of the thyroid

Oedema Water retention Lymphoedema Accumulation of lymph fluid Abnormal swelling Cause Lymphatic vessels damaged Lymph node removal Lymphatic fluid builds up as lymph system cant cope Protein rich fluids build up and swelling begins Excess Fluid in the interstitial compartment resulting in tissue swelling Causes Lymphatic blockages, impairment in body diluting urine Renal failure Liver failure

Infectious Mononucleosis Lymphadenitis Glandular Fever Young adults & teenagers. Virus is contagious Passed on by close contact. Antibodies created which provide lifelong immunity Rare to have more than one bout of glandular fever. Inflammation of a lymph node Complication bacterial infection of a wound Can be caused by virus

Cellulite Dimpled appearance of skin Caused by fat deposits just below the surface skin. It generally appears on skin in the abdomen, lower limbs, and pelvic region