Information on Lymphology
Lymphatic system and lymph
Our body consists of three large vascular systems: The arterial and venous vascular system as well as the lymphatic system. Arteries and veins together form the closed circulatory system. Coming from the heart, the arteries carry oxygen- and nutrient-rich blood into the body. The arteries branch into even thinner vessels up to the capillaries. From these a serum (blood plasma) is filtered into the interstitium (space between cells) and supplies the tissue with all necessary substances. The venous side of the capillaries then absorbs 90% of the filtered liquid.
The remaining 10% of the liquid drains from the tissue into the open-ended lymphatic system, together with proteins, metabolites, inflammatory products, pathogens and other foreign bodies. All those substances together form the „lymph-obligatory load“. That is why the lymphatic system is sometimes also called the „absorbent vessel system“.
The lymphatic system absorbs approximately six to eight liters of fluid from the tissue per day. As from this moment on the fluid is called „lymph“ (Greek word for "spring water"). It is of clear, slightly yellowish color; only the lymph from the bowel area is milky and dull, especially after a rich and fatty meal. The lymph reaches the circulatory system via precollectors, collectors and lymphatic ducts. Transport is provided by lymphangions ("small lymph hearts"), movement of muscles and joints, the pulse rate of the heart and breathing-related changing pressure in the chest as well as bowel motion.
The lymphangions are integrated into larger lymphatic vessels and have valve flats on the input and output sides, which allow the lymph to only flow into one direction. The musculature of the vascular wall between the valves is controlled by the vegetative nervous system. Lymphangions have a "beat" similar to the one of the heart, just much slower (six to nine times per minute).
Lymph nodes are to be found along the course of the lymphatic vessels. A healthy body possesses approximately 600 to 700 of them. They occur in large numbers, especially in the lateral area of the head and neck, in the armpits and in the area of the loins. They represent highly efficient "sewage purification plants" and free the lymph from pathogens and pollutants. If tumor cells enter the lymph nodes, they often attach to them and develop new tumors (metastases). Therefore it is important to also remove the lymph nodes during a cancer surgery, as only this way it can be determined whether they are infected as well.
The lymph nodes filter the water from the lymph and return it to the venous circulation. This way only about two liters of the absorbed lymph quantity enter the blood circulatory system. Responsible for this procedure are the "venous angles" (right behind the collar bones), situated closely to the heart.
The lymphatic system has only got a certain transporting capacity, which reflects the highest possible amount of lymph-obligatory load that can be removed per time unit. If the transporting capacity is limited, fluid remains in the tissue and forms a lymphedema
Venous vascular system
Arterial vascular system