Browse the corpus

The lymphatic system is a system that drains the leaked tissue fluid back into the circulation. Its components are lymphatic vessels, lymphatic organs, lymph nodes, and widely scattered lymphoid tissue within the connective tissue. Lymph is the tissue fluid flowing through these lymphatic channels. Lymphatic vessels contain valves that prevent the backflow of transported lymph.[1] The lymphatic vessels are so thin that the mere presence of valves gives the lymphatic channels the beaded appearance. Lymph flow from the peritoneum navigates through the thoracic duct to the intrathoracic lymph nodes.[2] This extracellular fluid then returns to the bloodstream.[3] Lymph is usually colorless, but that flowing from the intestinal organs is whitish (milky) due to the massive deposition of fat droplets within it and referred to as chyle. The lymphatic system in the gastrointestinal (GI) tract helps regulate the transport of chyle and balance interstitial fluid. A stimulant, such as feeding, activates lymph flow in the GI tract. It is also activated by cholecystokinin (CCK), glucagon, endothelin, bradykinin, substance-P, dopamine, serotonin, and many more. Lymph flow in the GI tract can also be inhibited by anti-diuretic hormone (ADH), vasoactive intestinal polypeptide (VIP), and acetylcholine. The lymphatic system in the intestines mainly functions to provide homeostasis in the GI tract by filtering fluids, blood cells, and plasma proteins that enter the tissue from the blood.[4] The regions above and below the umbilicus drain into axillary lymph nodes and superficial inguinal nodes, respectively. Thus a watershed line is formed horizontally passing through the umbilicus where the lymphatic channels do not cross.[5] The superficial inguinal nodes also receive lymph from the buttocks, penis, scrotum, labium majus, and the lower parts of the anal canal and vagina. This system eventually leads to the external iliac nodes, and finally, the lumbar aortic nodes. The pre-aortic nodes encompass the following nodes: celiac, superior mesenteric, and inferior mesenteric. These nodes drain lymph from the GI tract, spleen, gallbladder, pancreas, and liver. The para-aortic nodes, also known as the lumbar aortic nodes, drain lymph from the kidneys, suprarenal glands, testes, ovaries, uterus, and uterine tubes.

Lymphatic vessels contain valves that prevent the backflow of transported lymph.[1] The lymphatic vessels are so thin that the mere presence of valves gives the lymphatic channels the beaded appearance. Lymph flow from the peritoneum navigates through the thoracic duct to the intrathoracic lymph nodes.[2] This extracellular fluid then returns to the bloodstream.[3] Lymph is usually colorless, but that flowing from the intestinal organs is whitish (milky) due to the massive deposition of fat droplets within it and referred to as chyle. The lymphatic system in the gastrointestinal (GI) tract helps regulate the transport of chyle and balance interstitial fluid. A stimulant, such as feeding, activates lymph flow in the GI tract. It is also activated by cholecystokinin (CCK), glucagon, endothelin, bradykinin, substance-P, dopamine, serotonin, and many more. Lymph flow in the GI tract can also be inhibited by anti-diuretic hormone (ADH), vasoactive intestinal polypeptide (VIP), and acetylcholine. The lymphatic system in the intestines mainly functions to provide homeostasis in the GI tract by filtering fluids, blood cells, and plasma proteins that enter the tissue from the blood.[4] The regions above and below the umbilicus drain into axillary lymph nodes and superficial inguinal nodes, respectively. Thus a watershed line is formed horizontally passing through the umbilicus where the lymphatic channels do not cross.[5] The superficial inguinal nodes also receive lymph from the buttocks, penis, scrotum, labium majus, and the lower parts of the anal canal and vagina. This system eventually leads to the external iliac nodes, and finally, the lumbar aortic nodes. The pre-aortic nodes encompass the following nodes: celiac, superior mesenteric, and inferior mesenteric. These nodes drain lymph from the GI tract, spleen, gallbladder, pancreas, and liver. The para-aortic nodes, also known as the lumbar aortic nodes, drain lymph from the kidneys, suprarenal glands, testes, ovaries, uterus, and uterine tubes. The lymphatic vessels are present in all the tissues except the bone marrow, eyeball, central nervous system, epidermis, cartilage, internal ear, teeth, cornea, and placenta.