Veins


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Related to Veins: capillaries, Spider veins

Veins

 

vessels that transport blood from organs and tissues to the heart. Veins of the systemic circulation collect blood saturated with carbon dioxide, metabolites, hormones produced by the endocrine glands, and other substances from organs and parts of the body and transport it to the right atrium. Veins of the pulmonary circulation return oxygen-enriched blood from the lungs to the left atrium. Food absorbed in the gastrointestinal tract is transferred to the general bloodstream through the portal vein system. The veins originate in the capillary network where venules are formed, and on coalescing the venules form veins. The venous wall is much thinner and more plastic than the arterial wall, and its musculature is relatively weakly developed. Blood pressure is very low in the veins and below atmospheric pressure in the large ones. The flow of blood in the veins is greatly affected by the respiratory movements of the chest (suction) and movements of the diaphragm, while the deep veins of the extremities are affected by muscular contractions. The venous valves along the bloodstream allow blood to flow only to the heart. The numerous nerve endings in the walls of certain large veins (superior and inferior venae cavae, portal vein, and others) take part in regulating blood circulation.

IU. I. DENISOV-NIKOL’SKII


Veins

 

(also, nerves), in plants, the fibrous vascular bundles in leaf blades that perform conducting and mechanical functions. Large veins are formed by several of these bundles and often include strands of mechanical tissues and parenchyma. They are usually in the form of ribs on the lower side (sometimes on the upper side) of a leaf blade. Veins are also located in the petals and sepals of flowers, in fruits, and in plant stems. Veins in insects are hollow, tubular, hardened thickenings in the wing membrane. After the adult insect passes through the pupal or nymphal stages, the veins fill with hemolymph. This creates pressure that straightens the wing. There are both longitudinal and transverse veins, which maintain the stability and aerodynamic properties of the wing.

References in classic literature ?
If it only puts him in the vein to leave his poor clerk fifty pounds, that's something; and I think I shook him yesterday.
For it is manifest that the tie, moderately straightened, while adequate to hinder the blood already in the arm from returning towards the heart by the veins, cannot on that account prevent new blood from coming forward through the arteries, because these are situated below the veins, and their coverings, from their greater consistency, are more difficult to compress; and also that the blood which comes from the heart tends to pass through them to the hand with greater force than it does to return from the hand to the heart through the veins.
Here, again, is another short extract--this time written in a more comical vein, to make people laugh:
In his veins, though, flowed the blood of the best of a race of mighty fighters, and back of this was the training of his short lifetime among the fierce brutes of the jungle.
But the winter has chilled my veins, and the frost has nipped my buds, and the storm has broken my branches, and I shall have no roses at all this year.
And so she did bleed him, but the vein she opened was not one of those that lie close and blue beneath the skin; deeper she cut than that, for she opened one of those veins through which the bright red blood runs leaping from the heart.
Drain the blood from men's veins and put in water instead, then there will be no more war
He stopped, out of breath, for the veins were standing out upon his forehead, and he remembered what the English doctor at Cape Coast Castle had told him.
The spirit of that wonderful country runs like the elixir of life itself through his veins.
There is your full name and parentage, tracing out the amount of foreign blood which I find is in your veins.
The sweat broke out upon his forehead, the blood seemed turned to ice in his veins.
Floweth there not a tainted, frothy, swamp-blood in thine own veins, when thou hast thus learned to croak and revile?