system /sys·tem/ (sis´tim)
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. a school or method of practice based on a specific set of principles.
alimentary system digestive s.
auditory system the series of structures by which sounds are received from the environment and conveyed as signals to the central nervous system; it consists of the outer, middle, and inner ear and the tracts in the auditory pathways.
autonomic nervous system the portion of the nervous system concerned with regulation of activity of cardiac muscle, smooth muscle, and glands, usually restricted to the sympathetic and parasympathetic nervous systems.
Bethesda System a classification of cervical and vaginal cytology used in cytopathologic diagnosis.
cardiovascular system the heart and blood vessels, by which blood is pumped and circulated through the body.
CD system [c luster d esignation] a system for classifying cell surface markers expressed by lymphocytes based on a computer analysis grouping similar monoclonal antibodies raised against human leukocyte antigens.
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 (CNS) the brain and spinal cord.
centrencephalic system the neurons in the central core of the brain stem from the thalamus to the medulla oblongata, connecting the two hemispheres.
chromaffin system the chromaffin cells of the body considered collectively.
circulatory system channels through which nutrient fluids of the body flow; often restricted to the vessels conveying blood.
colloid system , colloidal system see colloid (2).
conduction system of heart a system of specialized muscle fibers that generate and transmit cardiac impulses and coordinate contractions, comprising the sinoatrial and atrioventricular nodes, bundle of His and its bundle branches, and subendocardial branches of Purkinje fibers.
digestive system the organs concerned with ingestion, digestion, and absorption of food or nutritional elements.
endocrine system the glands and other structures that elaborate and secrete hormones that are released directly into the circulatory system, influencing metabolism and other body processes; included are the pituitary, thyroid, parathyroid, and adrenal glands, pineal body, gonads, pancreas, and paraganglia.
enteric nervous system the enteric plexus, sometimes considered separately from the autonomic nervous system because it has independent local reflex activity.
extrapyramidal system a functional, rather than anatomical, unit comprising the nuclei and fibers (excluding those of the pyramidal tract) involved in motor activities; they control and coordinate especially the postural, static, supporting, and locomotor mechanisms. It includes the corpus striatum, subthalamic nucleus, substantia nigra, and red nucleus, along with their interconnections with the reticular formation, cerebellum, and cerebrum.
genitourinary system urogenital s.
haversian system a haversian canal and its concentrically arranged lamellae, constituting the basic unit of structure in compact bone (osteon).
heterogeneous system a system or structure made up of mechanically separable parts, as an emulsion or a suspension.
His-Purkinje system a portion of the conducting system of the heart, usually referring specifically to the segment beginning with the bundle of His and ending at the terminus of the Purkinje fiber network within the ventricles.
homogeneous system a system or structure made up of parts which cannot be mechanically separated, as a solution.
hypophysioportal system , hypothalamo-hypophysial portal system the venules connecting the capillaries (gomitoli) in the median eminence of the hypothalamus with the sinusoidal capillaries of the adenohypophysis.
immune system a complex system of cellular and molecular components having the primary functions of distinguishing self from not self and of defense against foreign organisms or substances.
International System of Units see SI unit, under unit.
keratinizing system the cells composing the bulk of the epithelium of the epidermis, which are of ectodermal origin and undergo keratinization and form the dead superficial layers of the skin.
limbic system a group of brain structures (including the hippocampus, gyrus fornicatus, and amygdala) common to all mammals; it is associated with olfaction, autonomic functions, and certain aspects of emotion and behavior.
locomotor system the structures in a living organism responsible for locomotion, in humans consisting of the muscles, joints, and ligaments of the lower limbs as well as the arteries and nerves that supply them.
lymphatic system the lymphatic vessels and lymphoid tissue, considered collectively.
lymphoid system the lymphoid tissue of the body, collectively; it consists of (a) a central component, including the bone marrow, thymus, and an unidentified portion called bursal equivalent tissue; and (b) a peripheral component consisting of lymph nodes, spleen, and gut-associated lymphoid tissue (tonsils, Peyer's patches).
lymphoreticular system the tissues of the lymphoid and reticuloendothelial systems considered together as one system.
masticatory system the bony and soft structures of the face and mouth involved in mastication, and the vessels and nerves supplying them.
metric system a decimal system of weights and measures based on the meter.
mononuclear phagocyte system (MPS) the set of cells consisting of macrophages and their precursors (blood monocytes and their precursor cells in bone marrow). The term has been proposed to replace reticuloendothelial system, which does not include all macrophages and does include other unrelated cell types.
muscular system the muscles of the body considered collectively; generally restricted to the voluntary, skeletal muscles.
nervous system the organ system which, along with the endocrine system, correlates the adjustments and reactions of the organism to its internal and external environment, comprising the central and peripheral nervous systems.
parasympathetic nervous system the craniosacral portion of the autonomic nervous system, its preganglionic fibers traveling with cranial nerves III, VII, IX, X, and XI, and with the second to fourth sacral ventral roots; it innervates the heart, smooth muscle and glands of the head and neck, and thoracic, abdominal, and pelvic viscera.
peripheral nervous system all elements of the nervous system (nerves and ganglia) outside the brain and spinal cord.
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 and liver.
Purkinje system a portion of the conducting system of the heart, usually referring specifically to the Purkinje network.
respiratory system respiratory tract; the tubular and cavernous organs that allow atmospheric air to reach the membranes across which gases are exchanged with the blood.
reticular activating system the system of cells of the reticular formation of the medulla oblongata that receive collaterals from the ascending sensory pathways and project to higher centers; they control the overall degree of central nervous system activity, including wakefulness, attentiveness, and sleep; abbreviated RAS.
reticuloendothelial system (RES) a group of cells having the ability to take up and sequester inert particles and vital dyes, including macrophages and macrophage precursors, specialized endothelial cells lining the sinusoids of the liver, spleen, and bone marrow, and reticular cells of lymphatic tissue (macrophages) and bone marrow (fibroblasts). See also mononuclear phagocyte s.
SI system see under unit.
stomatognathic system structures of the mouth and jaws, considered collectively, as they subserve the functions of mastication, deglutition, respiration, and speech.
sympathetic nervous system (SNS) the thoracolumbar part of the autonomic nervous system, the preganglionic fibers of which arise from cell bodies in the thoracic and first three lumbar segments of the spinal cord; postganglionic fibers are distributed to the heart, smooth muscle, and glands of the entire body.
urinary system the organs and passageways concerned with the production and excretion of urine, including the kidneys, ureters, urinary bladder, and urethra.
urogenital system the urinary system considered together with the organs of reproduction.
vascular system circulatory s.
visual system the series of structures by which visual sensations are received from the environment and conveyed as signals to the central nervous system; it consists of the photoreceptors in the retina and the afferent fibers in the optic nerve, chiasm, and tract.
| vascular system n. See circulatory system. |   Anterior view with veins shown in black. For veins and arteries that occur on both sides of the body, only one is labeled; eg., the right femoral vein has a matching left femoral vein. |
vascular
pertaining to blood vessels or indicative of a copious blood supply.
vascular clamps
see hemostatic forceps.
vascular clip
see clip (1).
vascular disease
vascular grafts
see vascular conduit.
vascular hemophilia
von Willebrand's disease.
vascular malformation
includes hamartoma, arteriovenous fistula, telangiectasia.
vascular neoplasm
listed elsewhere; these include hemangioma, hemangioendothelioma, hamartoma, telangiectasia, angiokeratoma, juvenile bovine angiomatosis, bovine cutaneous angiomatosis, varicose scrotal tumor, meningioangioma, lymphomatoid granulomatosis, lymphangioma, glomangioma, hemangiosarcoma, lymphangiosarcoma.
vascular nevus
irregular shaped, cutaneous mass, congenital, hair-covered initially, subsequently hairless, usually 1-2 inches diameter in foals, may be inflamed, ulcerated; composed of densely packed blood vessels and bleed easily: most located on lower limbs; see also nevus.
vascular occlusive syndrome
complete occlusion of the vessel supplying blood to a part of the body causes temporary loss of function or death of the part, fall in temperature and change in color.
vascular plaque
a minor lesion in animals; manifested by slight thickening and wrinkling of the intima of the vessel over oval or elongated elevations.
vascular pole
the point on the renal glomerulus where the blood vessels enter and exit.
vascular prosthesis
see vascular conduit.
vascular ring anomaly
see vascular ring.
vascular sinus transformation
marked dilation of sinuses in lymph nodes because of blockage of drainage from the node.
vascular stasis
serious slowing, or complete cessation, of blood or lymph flow through vessels.
vascular system
the vessels of the body including aorta, arteries, arterioles, capillaries, venules, sinusoids, sinuses, veins, lymphatics.
vascular tone
the state of contractile tension in the vessel walls.
vascular tumor
see vascular neoplasm (above).
vascular tunic
of the eye; consists of the choroid coat, the ciliary body and the iris.
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