The lymphatic system is one of the main components of the immune system and is composed of a network of organs, ducts and lymph nodes.The set of tissues and organs that participate in the immune response is known as the lymphatic system. It is constituted by organs, vessels, lymph nodes and lymphatic tissue. This system fulfills three basic functions:Defense: in lymph nodes, lymphocytes reproduce to respond to antigens.Fat absorption: most of the fats are absorbed by the lymphatic system and transported later to the blood.Capillary exchange: recover substances that the blood flow has lost in the capillary exchange.The lymphoid organs are divided into two groups:Primary or centralThe process known as lymphopoiesis, which consists of the maturation of lymphocytes, occurs. These obtain specific receptors for each type of antigen. The organs of this group are the thymus (mature T lymphocytes) and the bone marrow (mature B lymphocytes).Secondary or peripheralThey provide the environment so that the lymphocytes can interrelate and have contact with the antigen, causing the immune response. The organs that participate in this process are the lymph nodes, the lymphatic tissue and the spleen.This system works in the following way: the lymph is collected by lymphatic capillaries and is then conducted to the lymphatic vessels. In the body there are two large ducts that drain the tissues, the thoracic and the right lymphatic. The first receives the lymph from more than half of the body and its journey ends in the left subclavian vein; the second, in as much, facilitates the exit of the lymph of the right part of the organism and finishes its route in the right subclavian vein.The lymph nodes are found throughout the body, but where they are most abundant are in the armpits, groin, neck and pelvis. They are formed by a small resistant capsule with small round nodules, which are mixed with the lymphatic vessels. In its internal part, it has lymphoid tissue, in which there are large numbers of lymphocytes and phagocytic cells. The lymph passes through the body through these ganglia, which have entry and exit channels.In the ganglia (present in the neck, axillae, groin, mediastinum and abdominal cavity) there are three zones:Bark, in which there are B cells and lymphoid follicles. These follicles can be primary or secondary.Paracortex, very rich in T lymphocytes.Marrow. In this area are mature lymphocytes that are ready to leave the ganglion.The mucosa-associated lymphoid tissue (MALT) is a grouping of non-encapsulated lymphoid tissue, located in the lamina propria and submucosal areas of the gastro-intestinal, respiratory and genitourinary tracts.SpleenThis organ is located below the diaphragm, on the left side of the abdomen. It is divided into three zones: a protective cortex (on the outside), a red pulp (inside and forming a network of ducts) and a white pulp (inside and is composed of immune cells).Its main functions are to protect the body against infection, filter the blood and store it until necessary and destroy the platelets and worn red blood cells.FeverThe body can respond to bacterial or viral infections by raising its body temperature above normal 37 ° C, to prevent the invaders from multiplying. This mechanism is known as fever or pyrexia and is often accompanied by sweating and thirst.The hypothalamus is the thermostat of the body, since it is the one that orders that this generates more heat.The lymphIt is a clear fluid that runs through the lymphatic vessels, thanks to the contractions of the muscles and arteries and the movement of the extremities of the body. It is poor in proteins, but rich in lipids and contains white blood cells and some microorganisms that are eliminated when passing through the lymph fi lter.The three functions performed by this liquid are to collect and return the interstitial fluid to the blood, protect the body from antigens and absorb the nutrients of the digestive system, transporting them, together with oxygen, to the blood circulation.TimoIt is located in the middle area of ??the body, behind the sternum. Inside there is a marrow full of T lymphocytes prepared to multiply. These came through the bloodstream from the red bone marrow. From the thymus they are expelled to the spleen and lymph nodes. Although this organ atrophies at a very young age (six years), it continues to function but with less activity.