Lymphatic System

Introduction Components: Functions: Lymph fluid Lymphatic vessels Lymph nodes and organs Functions: Drains excess interstitial fluid – return this fluid to the blood stream Transport fats from the digestive tract to the bloodstream Immune responses

The Lymphatic System FG23_01.JPG Title: Lymphatic System Notes: An overview of the arrangement of lymphatic vessels, lymph nodes, and lymphoid organs. Keywords: lymphatic system, components, lymph nodes, cervical, axillary, pelvic, inguinal, lumbar, right lymphatic duct, thoracic lymphatic duct, mammary gland, spleen, gut-associated, cisterna chyli, thymus, lymphatics of lower limb

Lymphatics Originate as lymph capillaries Allow fluid to enter but not exit through one way valves Capillaries unite to form larger vessels Resemble veins in structure Connect to lymph nodes at various intervals Lymphatics ultimately deliver lymph into 2 main channels Right lymphatic duct Drains right side of head & neck, right arm, right thorax Empties into the right subclavian vein Thoracic duct Drains the rest of the body Empties into the left subclavian vein

Lymph Capillaries

Lymphatic Vessels

Main Channels of Lymphatics FG23_04.JPG Title: Lymphatic Ducts and Lymphatic Drainage Notes: The thoracic duct collects lymph from tissues inferior to the diaphragm and from the left side of the upper body. The right lymphatic duct drains the right half of the body superior to the diaphragm. Keywords: lymphatic ducts, circulatory system, jugular trunk, thoracic lymphatic duct, subclavian trunk, thoracic lymph nodes, intestinal trunk, cisterna chyli, azygos vein, right lymphatic duct

Lymph Nodes Oval structures located along lymphatics Enclosed by a fibrous capsule Lymph enters nodes through afferent lymphatics, flows through sinuses, exits through efferent lymphatic Contain high concentrations of immune system cells (white blood cells) Memory immune cells detect foreign molecules and are activated

Lymph Node

Immune responses Upon encountering a foreign molecules memory cells are activated and create an immune response The immune response involves cells not bound to the lymph nodes which then replicate and move throughout the body via the lymphatic/cardiovascular systems.

Tonsils Multiple groups of large lymphatic nodules Location – mucous membrane of the oral and pharyngeal cavities Palatine tonsils Posterior-lateral walls of the oropharynx Pharyngeal tonsil Posterior wall of nasopharynx Lingual tonsils Base of tongue

Tonsils

Spleen Largest lymphatic organ Located between the stomach & diaphragm Many of the same functions as lymph nodes Located between the stomach & diaphragm Additional functions Removes worn out/defective/ruptured red blood cells (RBC) Storage of platelets Production of new RBC

Spleen FG23_17B.JPG Title: The Spleen Notes: (a) The shape of the spleen roughly conforms to the shapes of adjacent organs; transverse section. (b)Visceral surface of intact spleen; major anatomical landmarks. (c)Histological appearance of the spleen. Keywords: spleen, transverse, abdominopelvic cavity, kidneys, pancreas, hilus, diaphragm, gastrosplenic ligament, stomach, liver, rib, white pulp, visceral surface, gastric area, splenic vein, splenic artery, renal area, histology, trabecular arteries, capsule, red pulp

Thymus Gland Located behind the sternum The capsule divides it into 2 lobes Function Differentiation and maturation of one type of lymphocytes (type of white blood cells)

Thymus Gland FG23_16A.JPG Title: The Thymus Notes: (a)Location of thymus on gross dissection. (b)Anatomical landmarks on thymus. (c)Low-power light micrograph of thymus. (d)Higher magnification showing structure of Hassall's corpuscles. Keywords: thymus, gross dissection, thyroid, trachea, lobe, septae, lobule, cortex, medulla, blood vessels, Hassall's corpuscles, epithelial cells, lymphocytes

Autoimmune diseases Autoimmune – self immunity Immune cells start to recognize your own cells as being foreign molecules. Can result in a number of different diseases depending on what is now considered to be foreign

Autoimmune diseases Type I diabetes (juvenile diabetes) Beta cells which produce insulin are targeted as foreign and destroyed by the immune system. Little to no insulin is produced This prevents uptake of glucose (sugar) by tissues Glucose is our main source of energy.

Rheumatoid Arthritis Pain swelling and stiffness in the joints Typically in the fingers and wrists Can affect other parts of the body such as eyes and lungs Exact cause is unknown

Sarcoidosis Commonly referred to in the TV show House, not sure why. Inflammation of the lungs, skin or lymph nodes

Narcolepsy Recent studies suggest this may be an autoimmune disease Uncontrolled sleep cycles May last a few seconds to several minutes long.