vein


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Related to vein: varicose vein, portal vein

vein,

blood vessel that returns blood to the heartheart,
muscular organ that pumps blood to all parts of the body. The rhythmic beating of the heart is a ceaseless activity, lasting from before birth to the end of life. Anatomy and Function

The human heart is a pear-shaped structure about the size of a fist.
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. Except for the pulmonary vein, which carries oxygenated blood from the lungs to the heart, veins carry deoxygenated blood. The oxygen-depleted blood passes from the capillariescapillary
, microscopic blood vessel, smallest unit of the circulatory system. Capillaries form a network of tiny tubes throughout the body, connecting arterioles (smallest arteries) and venules (smallest veins).
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 to the venules (small veins). The venules feed into larger veins, which eventually merge into the superior and inferior vena cavae, large vessels that consolidate the blood flow from the head, neck, and arms and from the trunk and legs, respectively (see also circulatory systemcirculatory system,
group of organs that transport blood and the substances it carries to and from all parts of the body. The circulatory system can be considered as composed of two parts: the systemic circulation, which serves the body as a whole except for the lungs, and the
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). The vena cavae direct the blood back into the heart. The walls of a vein are formed of three layers like the walls of an artery. However, these layers are thinner and less muscular and collapse when empty. With such notable exceptions as the portal system, most veins contain valves, formed by pouches in their inner coats, that keep the blood from flowing backward. Valves are most numerous in the veins of the extremities, and are absent in the smallest veins. Veins are subject to inflammation, dilatation or enlargement (as in a varicose veinvaricose vein,
superficial vessel that is abnormally lengthened, twisted, or dilated, seen most often on the legs and thighs. Varicose veins develop spontaneously, and are usually attributed to a hereditary weakness of the vein; the valves in the vein that keep the blood
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), rupture, and blockage by blood clots (thrombosisthrombosis
, obstruction of an artery or vein by a blood clot (thrombus). Arterial thrombosis is generally more serious because the supply of oxygen and nutrition to an area of the body is halted.
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).

Vein

 

a mineral body filling a fissure in rock. Simple veins are single mineralized fissures; complex veins are clusters of interwoven fissures or of zones of fracturing or schist formation. According to their morphological details veins are called lenticular, chambered, saddle-reef, ladder, or feather. Veins that cut across the layers of enclosing rock are called intersecting veins; those that lie in conformity with the stratification and dip of the enclosing rock are called stratified. The length of veins of mineral products varies from 1 m or less to 200 km—for example, the veins of gold ore in California. In terms of dip some veins taper off close to the earth’s surface, and others, for example, the vein of the Kolar deposit in India, are worked at a depth of more than 3 km. A vein has a geological and a working thickness, the minimum thickness for exploiting the vein deposit. Depending on the value of the constituent minerals, the working thickness of a vein may vary from several centimeters to dozens of meters.

vein

[vān]
(anatomy)
A relatively thin-walled blood vessel that carries blood from capillaries to the heart in vertebrates.
(botany)
One of the vascular bundles in a leaf.
(geology)
A mineral deposit in tabular or shell-like form filling a fracture in a host rock.
(invertebrate zoology)
One of the thick, stiff ribs providing support for the wing of an insect.
A venous sinus in invertebrates.

vein

1. any of the tubular vessels that convey oxygen-depleted blood to the heart
2. any of the hollow branching tubes that form the supporting framework of an insect's wing
3. any of the vascular strands of a leaf
4. a clearly defined mass of ore, mineral, etc., filling a fault or fracture, often with a tabular or sheetlike shape
5. a natural underground watercourse
References in periodicals archive ?
So many people suffer unknowingly from vein disease.
At the Renaissance Laser and Vein Institute, laser vein removal is performed under local anesthesia and typically takes less than an hour.
The external jugular vein began at the angle of the mandible as the continuation of posterior division of retromandibular and passed at first superficial to the sternocleidomastoid muscle, then deep to the muscle and drained into the internal jugular vein above the midpoint of the line joining the angle of the mandible to the middle of the clavicle.
Fujitsu's contactless palm vein authentication technology will be implemented for the first time in a library system to provide a lending service that eliminates the use of library identification (ID) cards to check out books.
In August this year, Hitachi established the Finger Vein Global Business Center within the Smart Identification Solutions Division in the Information & Telecommunication Systems Group.
The work-up revealed a left internal jugular vein thrombosis, and it was later found that the patient had hyperhomocysteinemia.
However, the key to vein reduction compound use is to be careful when adding the compounds into core sand mixtures, as they can result in varying degrees of reduction in mold tensile properties.
Are varicose veins a cosmetic problem or a medical problem?
Blood pressure stays quite low in the giraffe's jugular vein, apparently allowing blood to cascade from the head down the neck with no siphoning of cerebral blood into a dispersed venous network, according to Hargens and Meyer.
Sometimes a chemical is injected around the vein to shrink the hemorrhoid.
In 2005, the US market for varicose vein treatment devices was valued at nearly $100 million and is expected to grow over 10% by 2010.
The report provides information on the key drivers and challenges of the Retinal Vein Occlusion Therapeutics market.