An Introduction to the Human Body
Thank you very much. MLD in the treatment for fibromyalgia is geared toward pain management gate-control theory Emmie Gorrell November 18, at 5: Another group of important secondary lymphoid structures is the mucosa-associated lymphoid tissues. Take the quiz Name That Thing Test your visual vocabulary with our question challenge! Articulations formed by the ulna and radius, Lateral view of proximal end of ulna. Based on the American Cancer Society's statistics:
Cells in the lymphatic system react to antigens presented or found by the cells directly or by other dendritic cells. When an antigen is recognized, an immunological cascade begins involving the activation and recruitment of more and more cells, the production of antibodies and cytokines and the recruitment of other immunological cells such as macrophages.
The study of lymphatic drainage of various organs is important in the diagnosis, prognosis, and treatment of cancer. The lymphatic system, because of its closeness to many tissues of the body, is responsible for carrying cancerous cells between the various parts of the body in a process called metastasis.
The intervening lymph nodes can trap the cancer cells. If they are not successful in destroying the cancer cells the nodes may become sites of secondary tumours.
Lymphadenopathy refers to one or more enlarged lymph nodes. Small groups or individually enlarged lymph nodes are generally reactive in response to infection or inflammation. This is called local lymphadenopathy.
When many lymph nodes in different areas of the body are involved, this is called generalised lymphadenopathy. Generalised lymphadenopathy may be caused by infections such as infectious mononucleosis , tuberculosis and HIV , connective tissue diseases such as SLE and rheumatoid arthritis , and cancers , including both cancers of tissue within lymph nodes, discussed below, and metastasis of cancerous cells from other parts of the body, that have arrived via the lymphatic system.
Lymphedema is the swelling caused by the accumulation of lymph, which may occur if the lymphatic system is damaged or has malformations. It usually affects limbs, though the face, neck and abdomen may also be affected. In an extreme state, called elephantiasis , the edema progresses to the extent that the skin becomes thick with an appearance similar to the skin on elephant limbs.
Causes are unknown in most cases, but sometimes there is a previous history of severe infection, usually caused by a parasitic disease , such as lymphatic filariasis. Lymphangiomatosis is a disease involving multiple cysts or lesions formed from lymphatic vessels.
Lymphedema can also occur after surgical removal of lymph nodes in the armpit causing the arm to swell due to poor lymphatic drainage or groin causing swelling of the leg. Treatment is by manual lymphatic drainage. There is no evidence to suggest that the effects of manual lymphatic drainage are permanent. Cancer of the lymphatic system can be primary or secondary. Lymphoma refers to cancer that arises from lymphatic tissue.
Lymphoid leukaemias and lymphomas are now considered to be tumours of the same type of cell lineage. They are called "leukaemia" when in the blood or marrow and "lymphoma" when in lymphatic tissue. They are grouped together under the name "lymphoid malignancy". Lymphoma is generally considered as either Hodgkin lymphoma or non-Hodgkin lymphoma.
Hodgkin lymphoma is characterised by a particular type of cell, called a Reed—Sternberg cell , visible under microscope. It is associated with past infection with the Epstein-Barr Virus , and generally causes a painless "rubbery" lymphadenopathy.
It is staged , using Ann Arbor staging. Chemotherapy generally involves the ABVD and may also involve radiotherapy. It is treated according to whether it is high-grade or low-grade , and carries a poorer prognosis than Hodgkin lymphoma.
Lymphangiosarcoma is a malignant soft tissue tumour , whereas lymphangioma is a benign tumour occurring frequently in association with Turner syndrome. Lymphangioleiomyomatosis is a benign tumour of the smooth muscles of the lymphatics that occurs in the lungs. Lymphoid leukaemia is another form of cancer where the host is devoid of different lymphatic cells. Hippocrates , in the 5th century BC, was one of the first people to mention the lymphatic system.
In his work On Joints , he briefly mentioned the lymph nodes in one sentence. Rufus of Ephesus , a Roman physician, identified the axillary, inguinal and mesenteric lymph nodes as well as the thymus during the 1st to 2nd century AD.
In the mid 16th century, Gabriele Falloppio discoverer of the fallopian tubes , described what is now known as the lacteals as "coursing over the intestines full of yellow matter.
The lacteals were termed the fourth kind of vessels the other three being the artery, vein and nerve, which was then believed to be a type of vessel , and disproved Galen's assertion that chyle was carried by the veins. But, he still believed that the lacteals carried the chyle to the liver as taught by Galen.
He suspected that fluid to be chyle as its flow increased when abdominal pressure was applied. He traced this fluid to the thoracic duct, which he then followed to a chyle-filled sac he called the chyli receptaculum, which is now known as the cisternae chyli ; further investigations led him to find that lacteals' contents enter the venous system via the thoracic duct.
The idea that blood recirculates through the body rather than being produced anew by the liver and the heart was first accepted as a result of works of William Harvey —a work he published in In , Olaus Rudbeck — , a Swede, discovered certain transparent vessels in the liver that contained clear fluid and not white , and thus named them hepatico-aqueous vessels. He also learned that they emptied into the thoracic duct and that they had valves.
He is also the one to have named them "lymphatic vessels. Galen's ideas prevailed in medicine until the 17th century. It was thought that blood was produced by the liver from chyle contaminated with ailments by the intestine and stomach, to which various spirits were added by other organs, and that this blood was consumed by all the organs of the body.
This theory required that the blood be consumed and produced many times over. Even in the 17th century, his ideas were defended by some physicians. Alexander Monro , of the University of Edinburgh Medical School , was the first to describe the function of the lymphatic system in detail.
Lithograph by Pierre Roche Vigneron. Lith de Gregoire et Deneux, ca. Lymph originates in the Classical Latin word lympha "water",  which is also the source of the English word limpid.
The adjective used for the lymph-transporting system is lymphatic. The adjective used for the tissues where lymphocytes are formed is lymphoid. Lymphatic comes from the Latin word lymphaticus , meaning "connected to water. From Wikipedia, the free encyclopedia. For the massage technique, see Manual lymphatic drainage.
Castleman's disease Chylothorax Kawasaki disease Kikuchi disease Lipedema Lymphangitis Lymphatic filariasis Lymphocytic choriomeningitis Solitary lymphatic nodule. Olaus Rudbeck in Biology portal Medicine portal. Primer to the immune response. Retrieved 12 November Gray's anatomy Thirty-fifth ed. Retrieved 26 October Dispensable but not irrelevant". The New York Times.
Archived from the original on Saunders Comprehensive Veterinary Dictionary 3rd ed. Retrieved — via The Free Dictionary by Farlex. Information, Surgery and Functions". Childrens Hospital of Pittsburgh - Chp. Lay summary — National Institutes of Health. These structures express all of the molecular hallmarks of lymphatic endothelial cells, are able to carry both fluid and immune cells from the cerebrospinal fluid, and are connected to the deep cervical lymph nodes.
The unique location of these vessels may have impeded their discovery to date, thereby contributing to the long-held concept of the absence of lymphatic vasculature in the central nervous system.
The discovery of the central nervous system lymphatic system may call for a reassessment of basic assumptions in neuroimmunology and sheds new light on the aetiology of neuroinflammatory and neurodegenerative diseases associated with immune system dysfunction. Webster's New World Medical Dictionary. Bulletin of Mathematical Biology.
Review of Medical Embryology. Retrieved Feb 25, Davidson's principles and practice of medicine 21st ed. Longo 19 March Harrison's Manual of Medicine. Aselli, Pecquet, Rudbeck, Bartholin". A History of the Discovery of the Circulation of the Blood. Svensk Medicinhistorisk Tidskrift in Swedish. International League of Antiquarian Booksellers.
Story of a Great Hospital: The Royal Infirmary of Edinburgh Lewis and Charles Short. A Latin Dictionary on Perseus Project. Oxford English Dictionary 3rd ed. Subscription or UK public library membership required. Organs of the lymphatic system.
Lymph capillary Lymphatic vessel. Lymph trunk Lymph Lymphangion. Anatomy of the lymphatic system. Facial buccinator nasolabial Mandibular Submandibular Submental. Deep anterior cervical pretracheal paratracheal prelaryngeal thyroid Deep lateral cervical superior deep cervical inferior deep cervical retropharyngeal jugulodigastric jugulo-omohyoid. Anterior cervical Lateral cervical Supraclavicular. Parasternal Intercostal Superior diaphragmatic Trachea and bronchi superior inferior bronchopulmonary paratracheal intrapulmonary.
Thoracic duct Right lymphatic duct Bronchomediastinal lymph trunk. Retroaortic Lateral aortic Preaortic Celiac gastric hepatic splenic Superior mesenteric mesenteric ileocolic mesocolic Inferior mesenteric pararectal. Iliac Common external internal Sacral Retroperitoneal lymph nodes. Lumbar lymph trunk Intestinal trunk Cisterna chyli. Inguinal deep Cloquet's node superficial Popliteal. Retrieved from " https: Lymphatic system Angiology Animal anatomy.
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Views Read Edit View history. In other projects Wikimedia Commons. The tradeoff for this increase in distance is that the force required to move the load must be greater than the mass of the load. For example, the biceps brachia of the arm pulls on the radius of the forearm, causing flexion at the elbow joint in a third class lever system.
A very slight change in the length of the biceps causes a much larger movement of the forearm and hand, but the force applied by the biceps must be higher than the load moved by the muscle. Nerve cells called motor neurons control the skeletal muscles.
Each motor neuron controls several muscle cells in a group known as a motor unit. When a motor neuron receives a signal from the brain, it stimulates all of the muscles cells in its motor unit at the same time.
The size of motor units varies throughout the body, depending on the function of a muscle. Muscles that need a lot of strength to perform their function—like leg or arm muscles—have many muscle cells in each motor unit.
One of the ways that the body can control the strength of each muscle is by determining how many motor units to activate for a given function. This explains why the same muscles that are used to pick up a pencil are also used to pick up a bowling ball. Muscles contract when stimulated by signals from their motor neurons.
Motor neurons release neurotransmitter chemicals at the NMJ that bond to a special part of the sarcolemma known as the motor end plate. The motor end plate contains many ion channels that open in response to neurotransmitters and allow positive ions to enter the muscle fiber. The positive ions form an electrochemical gradient to form inside of the cell, which spreads throughout the sarcolemma and the T-tubules by opening even more ion channels.
Tropomyosin is moved away from myosin binding sites on actin molecules, allowing actin and myosin to bind together. ATP molecules power myosin proteins in the thick filaments to bend and pull on actin molecules in the thin filaments.
Myosin proteins act like oars on a boat, pulling the thin filaments closer to the center of a sarcomere. As the thin filaments are pulled together, the sarcomere shortens and contracts. Myofibrils of muscle fibers are made of many sarcomeres in a row, so that when all of the sarcomeres contract, the muscle cells shortens with a great force relative to its size. Muscles continue contraction as long as they are stimulated by a neurotransmitter.
When a motor neuron stops the release of the neurotransmitter, the process of contraction reverses itself. Calcium returns to the sarcoplasmic reticulum; troponin and tropomyosin return to their resting positions; and actin and myosin are prevented from binding. Sarcomeres return to their elongated resting state once the force of myosin pulling on actin has stopped. Certain conditions or disorders, such as myoclonus, can affect the normal contraction of muscles.
You can learn about musculoskeletal health problems in our section devoted to diseases and conditions. Also, learn more about advances in DNA health testing that help us understand genetic risk of developing early-onset primary dystonia.
A single nerve impulse of a motor neuron will cause a motor unit to contract briefly before relaxing. This small contraction is known as a twitch contraction. If the motor neuron provides several signals within a short period of time, the strength and duration of the muscle contraction increases.
This phenomenon is known as temporal summation. If the motor neuron provides many nerve impulses in rapid succession, the muscle may enter the state of tetanus, or complete and lasting contraction. A muscle will remain in tetanus until the nerve signal rate slows or until the muscle becomes too fatigued to maintain the tetanus. Not all muscle contractions produce movement. Isometric contractions are light contractions that increase the tension in the muscle without exerting enough force to move a body part.
When people tense their bodies due to stress, they are performing an isometric contraction. Holding an object still and maintaining posture are also the result of isometric contractions. A contraction that does produce movement is an isotonic contraction.
Isotonic contractions are required to develop muscle mass through weight lifting. Muscle tone is a natural condition in which a skeletal muscle stays partially contracted at all times. All muscles maintain some amount of muscle tone at all times, unless the muscle has been disconnected from the central nervous system due to nerve damage.
Skeletal muscle fibers can be divided into two types based on how they produce and use energy: Type I and Type II. Muscles get their energy from different sources depending on the situation that the muscle is working in. Muscles use aerobic respiration when we call on them to produce a low to moderate level of force. Aerobic respiration requires oxygen to produce about ATP molecules from a molecule of glucose.
Aerobic respiration is very efficient, and can continue as long as a muscle receives adequate amounts of oxygen and glucose to keep contracting. When we use muscles to produce a high level of force, they become so tightly contracted that oxygen carrying blood cannot enter the muscle. This condition causes the muscle to create energy using lactic acid fermentation, a form of anaerobic respiration. Anaerobic respiration is much less efficient than aerobic respiration—only 2 ATP are produced for each molecule of glucose.
Muscles quickly tire as they burn through their energy reserves under anaerobic respiration. To keep muscles working for a longer period of time, muscle fibers contain several important energy molecules. Myoglobin, a red pigment found in muscles, contains iron and stores oxygen in a manner similar to hemoglobin in the blood.
The oxygen from myoglobin allows muscles to continue aerobic respiration in the absence of oxygen. Another chemical that helps to keep muscles working is creatine phosphate. Creatine phosphate donates its phosphate group to ADP to turn it back into ATP in order to provide extra energy to the muscle. Finally, muscle fibers contain energy-storing glycogen, a large macromolecule made of many linked glucoses.
Active muscles break glucoses off of glycogen molecules to provide an internal fuel supply. When muscles run out of energy during either aerobic or anaerobic respiration, the muscle quickly tires and loses its ability to contract. This condition is known as muscle fatigue. A fatigued muscle contains very little or no oxygen, glucose or ATP, but instead has many waste products from respiration, like lactic acid and ADP. The body must take in extra oxygen after exertion to replace the oxygen that was stored in myoglobin in the muscle fiber as well as to power the aerobic respiration that will rebuild the energy supplies inside of the cell.
Oxygen debt or recovery oxygen uptake is the name for the extra oxygen that the body must take in to restore the muscle cells to their resting state. This explains why you feel out of breath for a few minutes after a strenuous activity—your body is trying to restore itself to its normal state.
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