Lymphatic system: Definition, anatomy, function, and diseases
Medical terminology for cancer: The Lymphatic System and Immune It is then transported through lymph vessels to lymph nodes, which clean and filter it. The lymph vessels work with the veins to return fluid from the tissues. in the production, maturation, and differentiation of immune T cells. . Cancer that starts in the lymphatic system is known as lymphoma. This could provide new insight into the relationship between the brain and the immune system. Introduction to the lymphatic system; Structures of the lymphatic system . only direct connection between the blood and lymph circulatory systems, .. Thymosin and other hormones it produces regulate the maturation and differentiation of T Cancer: The lymphatic system is key to distribution of metastatic.
These are created when cancer cells spread from the primary site via the bloodstream or lymphatic system and become attached to other organs. From there they begin to divide and invade space. Different cancers typically metastasise in certain organs.
The most common metastases occur in the liver, lungs, adrenal glands, brain and bones. The symptoms caused by metastases vary according to their location. Cancer tissue types Cancers are named according to the location of the primary site tumour and the structure of the tumour tissue. Epithelium the outer layer of the skin and mucosa Supportive tissue bone, cartilage, connective tissue, muscle tissue Nerve tissue Lymphatic tissue Bone marrow The epithelium covers the whole surface of the body and wraps all of its internal surfaces and cavities.
The surface of the skin, mucosa, gastrointestinal tract and bladder are exampled of epithelial tissue. Cancer that develops from the epithelial tissue is a carcinoma. Cancer that develops from supportive tissue is a sarcoma. Only a few regions, including the epidermis of the skinthe mucous membranesthe bone marrowand the central nervous systemare free of lymphatic capillaries, whereas regions such as the lungsgutgenitourinary systemand dermis of the skin are densely packed with these vessels.
Once within the lymphatic system, the extracellular fluid, which is now called lymphdrains into larger vessels called the lymphatics. These vessels converge to form one of two large vessels called lymphatic trunks, which are connected to veins at the base of the neck.
One of these trunks, the right lymphatic duct, drains the upper right portion of the body, returning lymph to the bloodstream via the right subclavian vein. The other trunk, the thoracic ductdrains the rest of the body into the left subclavian vein.
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Lymph is transported along the system of vessels by muscle contractions, and valves prevent lymph from flowing backward. The lymphatic vessels are punctuated at intervals by small masses of lymph tissue, called lymph nodesthat remove foreign materials such as infectious microorganisms from the lymph filtering through them. Role in immunity In addition to serving as a drainage network, the lymphatic system helps protect the body against infection by producing white blood cells called lymphocyteswhich help rid the body of disease-causing microorganisms.
The organs and tissues of the lymphatic system are the major sites of production, differentiation, and proliferation of two types of lymphocytes—the T lymphocytes and B lymphocytes, also called T cells and B cells. Although lymphocytes are distributed throughout the body, it is within the lymphatic system that they are most likely to encounter foreign microorganisms.
Fluid balance The lymphatic system helps maintain fluid balance. It returns excess fluid and proteins from the tissues that cannot be returned through the blood vessels. The fluid is found in tissue spaces and cavities, in the tiny spaces surrounding cells, known as the interstitial spaces. These are reached by the smallest blood and lymph capillaries.
Around 90 percent of the plasma that reaches tissues from the arterial blood capillaries is returned by the venous capillaries and back along veins. The remaining 10 percent is drained back by the lymphatics. Each day, around liters is returned. This fluid includes proteins that are too large to be transported via the blood vessels.
Loss of the lymphatic system would be fatal within a day. Without the lymphatic system draining excess fluid, our tissues would swell, blood volume would be lost and pressure would increase. Absorption Most of the fats absorbed from the gastrointestinal tract are taken up in a part of the gut membrane in the small intestine that is specially adapted by the lymphatic system.
The lymphatic system has tiny lacteals in this part of the intestine that form part of the villi. These finger-like protruding structures are produced by the tiny folds in the absorptive surface of the gut. Lacteals absorb fats and fat-soluble vitamins to form a milky white fluid called chyle.
This fluid contains lymph and emulsified fats, or free fatty acids. It delivers nutrients indirectly when it reaches the venous blood circulation. Blood capillaries take up other nutrients directly. The immune system The lymphatic system produces white blood cells, or lymphocytes that are crucial in fending off infections.
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The third function is to defend the body against unwanted organisms. Without it, we would die very soon from an infection. Our bodies are constantly exposed to potentially hazardous micro-organisms, such as infections. The body's first line of defense involves: In this case, the lymphatic system enables our immune system to respond appropriately. If the immune system is not able to fight off these micro-organisms, or pathogens, they can be harmful and even fatal. A number of different immune cells and special molecules work together to fight off the unwanted pathogens.
How does the lymphatic system fight infection? The lymphatic system produces white blood cells, known as lymphocytes. There are two types of lymphocyte, T cells and B cells.
They both travel through the lymphatic system. As they reach the lymph nodes, they are filtered and become activated by contact with viruses, bacteria, foreign particles, and so on in the lymph fluid.
From this stage, the pathogens, or invaders, are known as antigens. As the lymphocytes become activated, they form antibodies and start to defend the body. They can also produce antibodies from memory if they have already encountered the specific pathogen in the past. Collections of lymph nodes are concentrated in the neck, armpits, and groin. We become aware of these on one or both sides of the neck when we develop so-called "swollen glands" in response to an illness.
It is in the lymph nodes that the lymphocytes first encounter the pathogens, communicate with each other, and set off their defensive response. Activated lymphocytes then pass further up the lymphatic system so that they can reach the bloodstream. Now, they are equipped to spread the immune response throughout the body, through the blood circulation.
The lymphatic system and the action of lymphocytes, of which the body has trillions, form part of what immunologists call the "adaptive immune response. Diseases The lymphatic system can stop working properly if nodes, ducts, vessels, or lymph tissues become blocked, infected, inflamed, or cancerous. Lymphoma Cancer that starts in the lymphatic system is known as lymphoma. It is the most serious lymphatic disease. Hodgkin lymphoma affects a specific type of white blood cell known as Reed-Sternberg cells.
Non-Hodgkin lymphoma refers to types that do not involve these cells.