lymphatic system

(lĭmfăt`ĭk), network of vessels carrying lymph, or tissue-cleansing fluid, from the tissues into the veins of the circulatory system. The lymphatic system functions along with the circulatory system in absorbing nutrients from the small intestines. A large portion of digested fats are absorbed via the lymphatic capillaries. Like the blood circulatory system, the lymphatic system is composed of fine capillaries that lie adjacent to the blood vessels. These merge into larger tributaries known as trunks, and these in turn merge into two still larger vessels called ducts. The thoracic and right lymphatic ducts empty into the venous system in the region of the collarbones. Lymph, a colorless fluid whose composition is similar to that of blood except that it does not contain red blood cells or platelets, and contains considerably less protein, is continuously passing through the walls of the capillaries. It transports nutrients to the cells and collects waste products. Most of the lymph returns to the venous capillaries; however, a small amount (about 10%) enters the terminal lymphatic capillaries and is returned to the blood via the lymphatic system. The fluid that flows through the lymphatic system is functionally important because it contains substances having large molecules (such as proteins and bacteria) that cannot enter the small pores of the venous capillaries. Along the lymphatic network in certain areas of the body (neck, armpit, groin, abdomen, chest) are small reservoirs, the lymph nodes, which collect bacteria and other deleterious agents from the lymph which passes through them, and act as a barrier against the entrance of these substances into the bloodstream. In a disease state, therefore, the lymph nodes may become filled with harmful material to the degree where they can be seen or felt; therefore, enlarged lymph nodes are of diagnostic importance. Such enlargement of the lymph nodes can be a warning sign of various kinds of cancer, including breast cancerbreast cancer,
cancer that originates in the breast. Breast cancer is the second leading cause of cancer death in women (following lung cancer). Although the vast majority of the cases occur in women, some men also get breast cancer.
..... Click the link for more information. and Hodgkin's diseaseHodgkin's disease,
a type of cancer of the lymphatic system. First identified in 1832 in England by Thomas Hodgkin, it is a type of malignant lymphoma. Incidence peaks in young adults and the elderly.
..... Click the link for more information. . In cases where a cancerous growth has developed, removal of lymph nodes may help to prevent its further spread. However, such a procedure also slows the flow of lymph and may thus render some of the body vulnerable to infection. See also lymphoma, non-Hodgkin'slymphoma, non-Hodgkin's,
any cancer of the lymphoid tissue (see lymphatic system) in which the Reed-Sternberg cells characteristic of Hodgkin's disease (the other category of lymphoma) are not present.
..... Click the link for more information. .

Lymphatic system

A system of vessels in the vertebrate body, beginning in a network of exceedingly thin-walled capillaries in almost all the organs and tissues except the brain and bones. This network is drained by larger channels, mostly coursing along the veins and eventually joining to form a large vessel, the thoracic duct, which runs beside the spinal column to enter the left subclavian vein at the base of the neck. The lymph fluid originates in the tissue spaces by filtration from the blood capillaries. While in the lymphatic capillaries it is clear and watery. However, at intervals along the larger lymphatic vessels, the lymph passes through spongelike lymph nodes, where it receives great numbers of cells, the lymphocytes, and becomes turbid.

The lymph nodes of mammals vary in number, size, form, and structure in different species. The amount of connective tissue of the lymph nodes, that is, the degree of development of the capsule and trabeculae, also varies in different mammals. Other lymphoid organs include the tonsils, thymus gland, and spleen, and in certain classes and groups of animals, structures which are confined to such groups, for instance, the bursa of Fabricius in the birds, a diverticulum from the lower end of the alimentary canal. See Spleen, Thymus gland, Tonsil

The functions of the lymphatics are to remove particulate materials such as molecular proteins and bacteria from the tissues; to transport fat from the intestine to the blood; to supply the blood with lymphocytes; to remove excess fluid; also to return to the bloodstream the protein which has escaped from the blood capillaries. Basically, the composition of lymph closely resembles that of the plasma; lymph contains all of the types of protein found in plasma, but in lower concentration. The composition of lymph varies to some extent from one part of the body to another. Thus, the lymph from the liver contains more protein than that from the skin.

The lymph nodes serve as filtering-out places for foreign particles, including microorganisms, because the lymph comes into intimate contact with the many phagocytic cells of the sinusoids. These macrophages are of both the fixed and free wandering types. In addition to the phagocytic function, lymphoid tissue produces antibodies, although the actual process of antibody formation is not well understood. See Cellular immunology, Phagocytosis

Lymphatic System

the complex of capillaries and other vessels that collect lymph from the tissues and organs and carry it to the venous system in vertebrates and man. The system also comprises the lymph nodes (“glands”), located along the course of the vessels. The lymphatic system returns to the circulatory system the fluid that filters from the capillaries into the tissues, transmits nutrients absorbed in the intestine, and plays a protective role by filtering off lymph in the lymph nodes. From the tissues, the lymph infiltrates the lymphatic capillaries, which originate with blind ends in the tissues and collect in small (and then larger) vessels and trunks. These flow into the veins (as a rule, in the areas of the body with the lowest blood pressure).

In accordance with the low pressure of lymph, all lymphatic vessels are very thin-walled. In fish, amphibians, and reptiles, these vessels form thin-walled dilations called lymphatic sinuses (for example, the subcutaneous sinuses of the frog). In amniotes and man, there are thick-walled dilations (called lymphatic cisterns) and lymph nodes, in which the vessels lose their own walls and turn into sinuses of the nodes. In man, as in all mammals, there is a large number of lymph nodes, located singly or in groups, mainly at the base of the tongue, in the vicinity of the pharynx, neck, and bronchi, in the axillary and inguinal areas, and, especially, in the mesentery and walls of the intestines.

The movement of lymph is accomplished by periodic pressure put on the vessels of the skeletal muscles and viscera, by the pulsation of the vessels themselves, and by the pressure of the fluid that is continuously entering the capillaries. In fish, amphibians, reptiles, and birds, lymph is actively pumped over by lymph hearts; in mammals, this is fostered by the suction effect of the thoracic cavity upon inhalation. In birds, mammals, and man, the vessels have pocketlike valves that allow the lymph to flow in one direction only.

The lymphatic system became distinct from the venous system during the course of evolution. In cyclostomes and sharks, the lymphatic system carries both lymph and blood. Extensively linked with the venous system, it is called the hemolymphatic system to distinguish it from the true lymphatic system of more highly organized vertebrates. The superficial lateral veins of the trunk in sharks became, in other fishes, the superficial lymphatic vessels, which pass along the sides of the body and into the tail and fins. In addition, fish have deep ducts that accompany the main circulatory trunks and discharge anteriorly into the anterior cardinal veins and posteriorly into the caudal vein (where, in some fishes, the lymphatic heart develops).

The lymphatic system of amphibians is similar to that of fish, but the development of lymph hearts (from two pairs in acaudates to 20 in caudates and 100 in apods) makes lymph circulation more active. Highly developed subcutaneous vessels and sinuses ensure against possible dehydration. In reptiles, lymph from the intestinal vessels and posterior extremities is collected in the lymphatic cistern, from which flow paired thoracic ducts. These, together with vessels from other parts of the body, flow into the jugular veins. The lymph hearts are preserved only at the base of the tail, and there are no lymph nodes (with the exception of one in the mesentery of crocodiles).

There are few nodes in birds; in some species, a lymph heart that pumps lymph into the veins of the kidneys is preserved at the base of the tail. Paired thoracic ducts open into the anterior venae cavae. Valves appear in the vessels for the first time in birds.

In mammals, the entry of lymph into the circulatory system is concentrated anteriorly: paired thoracic ducts originate at the chyle cistern of the mammary sinus (where lymph from the intestine and posterior half of the body is collected), receiving vessels from the rest of the trunk and flowing into the superior venae cavae.

In man only the left thoracic duct, located asymmetrically, is preserved, beginning at the chyle cistern and discharging into the left angulus venosus (the junction of the left subclavian and interior jugular veins). Lymph from the right side of the upper half of the body flows into the circulatory system through the right lymphatic duct.

REFERENCES

Zhdanov, D. A. Funktsional’naia anatomiia limfaticheskoi sistemy. Gorky, 1940.
Zhdanov, D. A. Obshchaia anatomiia i fiziologiia limfaticheskoi sistemy. [Leningrad] 1952.
Shmal’gauzen, I. I. Osnovy sravnitel’noi anatomii pozvonochnykh zhivotnykh, 4th ed. Moscow, 1947.V. B. SUKHANOV

lymphatic system

[lim′fad·ik ‚sis·təm] (anatomy) A system of vessels and nodes conveying lymph in the vertebrate body, beginning with capillaries in tissue spaces and eventually forming the thoracic ducts which empty into the subclavian veins.

lymphatic system

an extensive network of capillary vessels that transports the interstitial fluid of the body as lymph to the venous blood circulation

Lymphatic system

lymphatic

[lim-fat´ik] 1. pertaining to lymph or to a lymphatic vessel.2. a lymphatic vessel.lymphatic ducts the two large vessels into which all lymphatic vessels converge. The right lymphatic duct joins the venous system at the junction of the right internal jugular and subclavian veins and carries lymph from the upper right side of the body. The left lymphatic duct, or thoracic duct, enters the circulatory system at the junction of the left internal jugular and subclavian veins; it returns lymph from the upper left side of the body and from below the diaphragm.lymphatic system the vessels" >lymphatic vessels and tissues" >lymphoid tissues considered collectively. (See also circulatory system.) Several diseases affect the lymphatic system. lymphogranuloma venereum is a viral disease that attacks lymph nodes in the groin and usually is transmitted by sexual contact. lymphadenitis is an inflammation of the lymph nodes, particularly in the neck; swollen tonsils is an example. Generalized lymphadenitis can be a symptom of the secondary stage of syphilis. Cancer attacks the lymphatic system, as it does other systems of the body; a tumor of the lymphoid tissue is known as a lymphoma. The general term lymphosarcoma refers to malignant neoplastic disorders of lymphoid tissue.

Diagrammatic representation of lymphatic drainage of various parts of the body. From Dorland's, 2000.

system

[sis´tem] 1. a set or series of interconnected or interdependent parts or entities (objects, organs, or organisms) that act together in a common purpose or produce results impossible by action of one alone. 2. an organized set of principles or ideas. adj., adj systemat´ic, system´ic.
The parts of a system can be referred to as its elements or components; the environment of the system is defined as all of the factors that affect the system and are affected by it. A living system is capable of taking in matter, energy, and information from its environment (input), processing them in some way, and returning matter, energy, and information to its environment as output.
An open system is one in which there is an exchange of matter, energy, and information with the environment; in a closed system there is no such exchange. A living system cannot survive without this exchange, but in order to survive it must maintain pattern and organization in the midst of constant change. Control of self-regulation of an open system is achieved by dynamic interactions among its elements or components. The result of self-regulation is referred to as the steady state; that is, a state of equilibrium. homeostasis is an assemblage of organic regulations that act to maintain steady states of a living organism.
A system can be divided hierarchically into subsystems, which can be further subdivided into sub-subsystems and components. A system and its environment could be considered as a unified whole for purposes of study, or a subsystem could be studied as a system. For example, the collection of glands in the endocrine system can be thought of as a system, each endocrine gland could be viewed as a system, or even specific cells of a single gland could be studied as a system. It is also possible to think of the human body as a living system and the endocrine system as a subsystem. The division of a system into a subsystem and its environment is dependent on the perspective chosen by the person studying a particular phenomenon.

Systems, subsystems, and suprasystems. Within the environment there are suprasystems, such as human society, and systems within the suprasystem, such as the educational and industrial systems and the health care delivery system. Within the health care delivery system are subsystems, such as the patient, family members, the nurse, the physician, and allied health care professionals and paraprofessionals.alimentary system digestive system.apothecaries' system see apothecaries' system" >apothecaries' system.autonomic nervous system see autonomic nervous system.avoirdupois system see avoirdupois system" >avoirdupois system.behavioral system in the behavioral system model of nursing, the patterned, repetitive, and purposeful behaviors of an individual.cardiovascular system the heart and blood vessels, by which blood is pumped and circulated through the body; see also circulatory system.CD system (cluster designation) a system for classifying markers" >cell-surface markers expressed by lymphocytes based on a computer analysis of monoclonal antibodies against hla antigens, with antibodies having similar specificity characteristics being grouped together and assigned a number (CD1, CD2, CD3, etc.); these CD numbers are also applied to the specific antigens recognized by the various groups of monoclonal antibodies. See also antigen" >CD antigen.centimeter-gram-second system (CGS) (cgs) a system of measurements in which the units are based on the centimeter as the unit of length, the gram as the unit of mass, and the second as the unit of time.central nervous system see central nervous system.centrencephalic system the neurons in the central core of the brainstem from the thalamus to the medulla oblongata, connecting the hemispheres" >cerebral hemispheres.circulatory system see circulatory system.client system in the general systems framework and theory of goal attainment" >general systems framework and theory of goal attainment, the composite of physiological, psychological, sociocultural, and developmental variables that make up the total person.colloid system (colloidal system) colloid (def. 3).conduction system (conductive system (of heart)) the system of atypical cardiac muscle fibers, comprising the sinoatrial and atrioventricular nodes, internodal tracts, atrioventricular bundle, bundle branch, and terminal ramifications into the Purkinje network.digestive system see digestive system.Emergency Medical Services (EMS) system a comprehensive program designed to provide services to the patient in the prehospital setting. The system is activated when a call is made to the EMS operator, who then dispatches an ambulance to the patient. The patient receives critical interventions and is stabilized at the scene. A communication system allows the health care workers at the scene to contact a trauma center for information regarding further treatment and disposition of the patient, followed by transportation of the patient to the most appropriate facility for treatment.endocrine system the system of ductless glands and other structures that produce internal secretions (hormones) that are released directly into the circulatory system, influencing metabolism and other body processes; see endocrine glands.environmental control system unit" >environmental control unit.expert system a set of computer programs designed to serve as an aid in decision making.extrapyramidal system see extrapyramidal system.gateway system a software interface between an online searcher and one or more search systems, facilitating the use of the system by searchers who are unfamiliar with it, or with online retrieval in general.genitourinary system the organs concerned with production and excretion of urine, together with the reproductive organs. (See Plates.) Called also urogenital system.haversian system a canal" >haversian canal and its concentrically arranged lamellae, constituting the basic unit of structure in compact bone (osteon).

Haversian system: Structures of compact and spongy bone with the central haversian canal surrounded by the lamellae. From Applegate, 2000.health care system see health care system.heterogeneous system a system or structure made up of mechanically separable parts, as an emulsion or suspension.His-Purkinje system the intraventricular conduction system from the bundle of His to the distal Purkinje fibers, which carries the impulse to the ventricles.Home Health Care Classification system see home health care classification system.homogeneous system a system or structure made up of parts that cannot be mechanically separated, as a solution.hypophyseoportal system (hypophysioportal system) (hypothalamo-hypophysial portal system) the venules connecting the hypothalamus with the sinusoidal capillaries of the anterior lobe of the pituitary gland; they carry releasing substances to the pituitary.immune system see immune system.interpersonal system in the general systems framework and theory of goal attainment, two or more individuals interacting in a given situation.lay health system a system comprising an informal referral network and sources of treatment outside the formal biomedical sources of health care; it includes individual consultation and information-seeking through significant others and peers concerning health behaviors, symptoms, and evaluation of treatment before, during, and after consultation with health care professionals.legal system in the omaha system, anything connected with law or its administration; it includes legal aid, attorney, courts, or Child Protective Services (CPS), and many other agencies and officials.limbic system a system of brain structures common to the brains of all mammals, comprising the phylogenetically old cortex (archipallium and paleopallium) and its primarily related nuclei. It is associated with olfaction, autonomic functions, and certain aspects of emotion and behavior.lymphatic system see lymphatic system.lymphoid system the lymphoid tissue of the body, collectively; it consists of primary (or central) lymphoid tissues, the bone marrow, and thymus, and secondary (or peripheral) tissues, the lymph nodes, spleen, and gut-associated lymphoid tissue (tonsils, Peyer's patches).lymphoreticular system the lymphoid and reticuloendothelial systems considered together; see also lymphoreticular disorders.metric system see metric system.mononuclear phagocyte system the group of highly phagocytic cells that have a common origin from stem cells of the bone marrow and develop circulating monocytes and tissue macrophages, which develop from monocytes that have migrated to connective tissue of the liver (kupffer's cells), lung, spleen, and lymph nodes. The term has been proposed to replace reticuloendothelial system, which includes some cells of different origin and does not include all macrophages.nervous system see nervous system.nursing system in the self-care model of nursing, all the actions and interactions of nurses and patients in nursing practice situations; nursing systems fall into three categories: wholly compensatory, partly compensatory, and supportive-educative.Omaha system see omaha system.oxygen delivery system a device that delivers oxygen through the upper airways to the lungs at concentrations above that of ambient air. There are two general types: the fixed performance or high flow type, which can supply all of the needs of a patient for inspired gas at a given fractional inspired oxygen; and the variable performance or low flow type, which cannot supply all of the patient's needs for oxygen and delivers fractional inspired oxygen that varies with ventilatory demand.parasympathetic nervous system see parasympathetic nervous system" >parasympathetic nervous system.peripheral nervous system the portion of the nervous system consisting of the nerves and ganglia outside the brain and spinal cord.personal system in the general systems framework and theory of goal attainment, the unified self, a complex whole that is rational, conscious, and feeling and that sets goals and decides on the means of achieving them.pituitary portal system hypothalamo-hypophysial portal system.portal system an arrangement by which blood collected from one set of capillaries passes through a large vessel or vessels and another set of capillaries before returning to the systemic circulation, as in the pituitary gland (the hypothalamo-hypophysial portal system) or the liver (the hepatic portal circulation).renin-angiotensin-aldosterone system see renin-angiotensin-aldosterone system.respiratory system the group of specialized organs whose specific function is to provide for the transfer of oxygen from the air to the blood and of waste carbon dioxide from the blood to the air. The organs of the system include the nose, the pharynx, the larynx, the trachea, the bronchi, and the lungs. See also respiration and Plates 7 and 8.reticular activating system see reticular activating system.reticuloendothelial system see reticuloendothelial system.safety system see safety system." >safety system.SI system see SI units.skeletal system see skeletal system.social system in the general systems framework and theory of goal attainment, an organized boundary system of social roles, behaviors, and practices developed to maintain balance for growth, development, and performance, which involves an exchange of energy and information between the person and the environment for regulation and control of stressors.support system in the omaha system, the circle of friends, family, and associates that provide love, care, and need gratification; it may include church, school, workplace, or other groupings.sympathetic nervous system see sympathetic nervous system.Unified Medical Language system see unified medical language system.Unified Nursing Language system see unified nursing language system.unit dose system a method of delivery of patient medications directly to the patient care unit. Following review by a nurse, a copy of the physician's original order is sent to the pharmacy, where the pharmacist reviews it again. The pharmacist then fills the order and delivers the medication to the patient care unit, usually in a 24-hour supply. Each patient has an individual supply of medications prepared and labeled by the pharmacist.urinary system the system formed in the body by the kidneys, ureters, urinary bladder, and urethra, the organs concerned in the production and excretion of urine.urogenital system genitourinary system.vascular system circulatory system.vasomotor system the part of the nervous system that controls the caliber of the blood vessels.

lymphoid system

[TA] it consists of lymphatic vessels, nodes, and lymphoid tissue; it empties into the veins at the level of the superior aperture of the thorax. Synonym(s): systema lymphoideum [TA], absorbent system, lymphatic system, systema lymphaticum

lymphatic system

n. The interconnected system of spaces and vessels between body tissues and organs by which lymph circulates throughout the body.

lymphatic system

THE LYMPHATIC SYSTEM

THE LYMPHATIC SYSTEM

THE LYMPHATIC SYSTEMA component of the circulatory system comprising: the lymphatics, and the lymphoid tissues, See: illustration; immune response; immune system; lymph

lymphatics

The lymphatics begin with lymphatic capillaries, permeable endothelial vessels one-cell thick, which absorb interstitial tissue fluid, particles, microbes, debris, and, from the small intestines, fat. Lymphatic capillaries empty into larger lymph vessels that eventually empty their contents (lymph) into the venous circulation through lymphatic ducts.

lymphoid tissues

Lymph nodes are interposed between lymph vessels at some of the junctions between vessels. As it percolates through a lymph node, lymph is modified: debris is filtered out, lymphocytes are activated, and antibodies and lymphocytes are added to the fluid. Other lymphoid tissues have similar functions: The spleen filters the circulating blood, to which it adds antibodies and lymphocytes. Tonsils, Peyer’s patches, and other unencapsulated lymphoid tissues line epithelia that are in contact with the outside environment; unencapsulated lymphoid tissues activate lymphocytes and manufacture antibodies against foreign antigens. Lymphoid tissues in the bone marrow are proliferation and activation centers for lymphocytes, and the thymus is a proliferation and maturation center for T lymphocytes, especially during the neonatal and early postnatal years.

lymphatic system

a system of tubules in vertebrates that drains excess tissue fluid (LYMPH) from the tissue spaces to the blood system. Unlike blood CAPILLARIES, lymph capillaries are blind-ending in the tissue spaces, gradually joining up to larger and larger vessels with two major lymphatic ducts entering the venous system in the upper thoracic cavity. Lymph is not moved along by heart contractions but (as in veins) by the action of skeletal muscles. Lymph vessels contain one-way valves to prevent backflow of fluid to the tissues.

Mammals and some birds possess clumps of lymphatic tissue called LYMPH NODES that act as filters for the removal of pathogens and are also sites of LYMPHOCYTE formation. Nodes are especially prevalent in the neck, underarm and groin, becoming swollen when adjacent to an infection. Besides returning excess water and protein to the blood system and being active in combating infection, lymph (rather than blood) transports fats from the gut wall, the lymph vessels being called LACTEALS since their contents are milky white.

Lymphatic system

A connected network of nodes, or glands, that carry lymph throughout the body. Lymph is a fluid that contains the infection-fighting white blood cells that form part of the body's immune system. Because the network goes throughout the body, cancer cells that enter the lymphatic system can travel to and be deposited at any point into the tissues and organs and form new tumors there.Mentioned in: Acute Lymphangitis, Elephantiasis, Filariasis, Fistula, Laryngeal Cancer, Ovarian Cancer, Radical Neck Dissection, Waldenström's Macroglobulinemia

lymphatic system

lymphatic system

lymphatic system

lymphat′ic sys`tem

lym·phat·ic system

lymphatic system

lymphatic system

lymphatic system

Lymphatic system

Lymphatic System

REFERENCES

lymphatic system

lymphatic system

Lymphatic system

lymphatic

system

lymphoid system

lymphatic system

lymphatic system

lymphatics

lymphoid tissues

lymphatic system

Lymphatic system

lymphatic system

Synonyms for lymphatic system

noun the interconnected system of spaces and vessels between body tissues and organs by which lymph circulates throughout the body

Synonyms

Related Words