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In mammals including humans, the lymphatic vessels (or lymphatics) are a network of thin tubes that branch, like blood vessels, into tissues throughout the body. Lymphatic vessels carry lymph, a colorless, watery fluid originating from interstitial fluid (fluid in the tissues). The lymphatic system transports infection-fighting cells called lymphocytes, is involved in the removal of foreign matter and cell debris by phagocytes and is part of the body's immune system. It also transports fats from the small intestine to the blood. The spleen, thymus and bone marrow are considered as lymphoid tissue. The spleen acts to filter and modify the blood while the bone marrow and thymus act to produce and mature lymphocytes and other immune cells. The lymphatic system consists of the lymphatics and the lymphoid tissue.
Unlike the circulatory system, the lymphatic system is not closed and has no central pump; the lymph moves slowly and under low pressure. Like veins, lymph vessels have one-way valves and depend mainly on the movement of skeletal muscleskeletal muscle Muscle is one of the four tissue types. The other three types are: epithelium, connective tissue and nervous tissue. The primary purpose of muscle tissue is to contract. Muscle contraction is used to move parts of the body, as well as to ms to squeeze fluid through them. Rhythmic contraction of the vessel walls may also help draw fluid into the lymphatic capillaries. This fluid is then transported to progressively larger lymphatic vessels culminating in the right lymphatic duct (for lymph from the right upper body) and the thoracic ductIn human anatomy, the thoracic duct is an important part of the lymphatic system it is the largest lymphatic vessel in the body. It collects most of the lymph in the body (except that from the right arm and the right side of the chest, neck and head, whic (for the rest of the body); these ducts drain into the circulatory system at the right and left subclavian vein s (near the shoulders).
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Major lymphatic vessels in humans |
Along this network of vessels are small organs called lymph nodeLymph nodes are components of the lymphatic system. Clusters of lymph nodes are found in the underarms, groin, neck, chest, and abdomen. Lymph nodes act as filters, with an internal honeycomb of connective tissue filled with lymphocytes that collect and ds. Clusters of lymph nodes are found in the underarms, groin, neck, chest, and abdomen. Lymph nodes act as filters, with an internal honeycomb of connective tissue filled with lymphocytes that collect and destroy bacteria and virusA common alternate meaning of virus is computer virus. Other meanings, as well as a discussion of pluralization, are at plural of virus''. bacteriophage (left center); an animal virus (top right); and a retrovirus (bottom right). Viruses depend on the hoses. When the body is fighting an infection, these lymphocytes multiply rapidly and produce a characteristic swelling of the lymph nodes.
Lymph originates as blood plasmaBlood plasma is a component of blood. It is the liquid in which blood cells are suspended. Blood plasma contains proteins, nutrients, metabolic end products, hormones, and inorganic electrolytes. Serum is the same as blood plasma except that clotting fact lost from the capillaryCapillaries are the smallest of the body's blood vessels. They connect arteries and veins. Capillaries have walls composed of a single layer of cells, the endothelium. This layer is so thin that molecules such as oxygen, water and lipids can pass through beds of the circulatory system, which leaks out into the surrounding tissues. Although capillaries lose only about 1% of the volume of the fluid that passes through them, so much blood circulates that the cumulative fluid loss in the average human body is about 3L per day. The lymphatic system collects this fluid by diffusion into lymph capillaries, and returns it to the circulatory system. Once within the lymphatic system the fluid is called lymph, and has almost the same composition as the original interstitial fluid.
Lymph vessels are present in the lining of the gastrointestinal tractFor the Physics term 'GUT', please refer to Grand unification theory The gastrointestinal or digestive tract also referred to as the GI tract or the alimentary canal or the gut is the system of organs within multicellular animals which takes in food, dige. Fats absorbed from food by the small intestine are passed on to the lymph, to be transported to the blood circulation via the thoracic duct. Unlike carbohydrates and proteins, ingested fats therefore pass to the circulation without any processing by the liver.
Whenever the lymphatic system cannot drain interstitial fluid from tissues faster than they accumulate, the resulting swelling is known as lymphedema. Cancers that develop from lymphocytes are known as lymphomas.
