Lymphatic System Mandatory Revision Questions and Correct Answers

functions of the lymphatic system - 1. drains excess interstitial fluid. lymphatic vessels drain excess fluid from tissue spaces and returns it to the blood 2. transports dietary lipids. lymphatic vessels transport lipids and lipid solubel vits (A,D,E and K) absorbed by the GI tract 3. carries out immune responses. initiates highly specific responses directed against particular microbes or abnormal cells. source of lymph - components of blood plasma filter freely through the capillary walls to form interstitial fluid but more fluid filters out of blood capillaries than returns to them by reabsorption. the excess filtered fluid drains into lymphatic vessels and becomes lymph. compare and contrast lymphatic vessels and blood vessels - blood capillaries converge to form venules and then veins, lymphatic capillaries unite to form larger lymphatic vessels whihc resemble veins in structure but have thinner walls and more valves. lymphatic vessels in the subcutaneous tissue generally follow route of veins. lymphatic vessels of the viscera follow route of arteries. lymphatic vessels close at one end causing only a one way path for lymph to flow. lacteals - located in the small intestine, are specialized lymphatic capillaries that carry dietary lipids into lymphatic vessels and ultimately into the blood. describe the flow of lymph - blood capillaries (blood) => interstitial spaces (interstitial fluid) => lymphatic capillaries (lymph) =>lymphatic vessels ( lymph) =>lymphatic ducts (lymph) => junction of the internal jugular and subclavian veins (blood) microscopic anatomy of thymus - enveloping layer of connective tissue holds the two lobes closely together but a connective tissue capsule separates the two. gross anatomy of thymus - thymic lobule consisting of a deeply staining outer cortex and a lighter staining central medulla. the cortex is composed of large numbers of T cells and scattered dendritic cells, epithelial cells and macrophages. dendritic cells - are derived from monocytes and so named because they have long branched projections that resemble the dendrites of a neuron, assist the maturation process. macrophages - help clear out the debris of dead and dying cells. medulla - consists of wodely scattered, more mature T cells, epithelial cells, dendritic cells, and macrophages