These parts of the lymphatic vessel system possess regular valves, an intima, a media, and an adventitia. Their diameter is about 40 to 100 mm, the thickness of the wall about 2 to 3 mm. The rhombic shape of the endothelial cells is similar to that in the venous system. All collectors possess a well-developed continuous basement membrane, often in close contact with collagenous and elastic fibers. Collectors have to carry the lymphatic fluid into the venous vessel system. The greatest lymph stem is the ductus thoracicus, which transports about 2.5 L lymph per day. The lymph is propelled by intrinsic forces of these vessels, which have their morphological correlation in the lymphangion structure. Each of those segments consist of parts between two valves (from 0.2 to several millimeters) and a strong muscular cuff. A slight dilatation of the vessel wall of a lym-phangion produces a contraction of the vessel wall. So the lymph is propelled in both directions, backward and forward. The act of closure of the distal and the opening of the proximal valves carries the lymph into the nearest proximal lymphangion. This autonomically repeated rhythmic action can modify by supplying a network of nervous fibers. The frequency of this action is 6 to 10 per minute, but values of 15 to 20 per minute are also possible. The resulting pressure is between 1 and 25mmHg, normally 3 to 5mmHg. This process was first described by Mislin and Rathnow . Pulsation of neighboring arteries and muscle and respiratory action are additional amplifying factors. So insufficient lymph flow can be supported by massage for treatment of edema.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.