Vessel that carries blood to the heart. Except for the pulmonary veins, veins bear deoxygenated blood from capillaries, which converge into threadlike venules and then veins, finally emptying into the venae cavae (see cardiovascular system; vena cava). Blood moves through veins by contraction of the surrounding muscles. Backflow is prevented by valves in most veins' inner layer (tunica intima), which lacks the elastic membrane lining of arteries. The thin middle layer (tunica media) is mostly collagen fibres, and the thick outer layer (tunica adventitia) is mostly connective tissue. Seealso circulation; varicose vein.

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or varix

Twisted vein distended with blood. Varix also covers arteries and lymphatic vessels (see lymphatic system). Varicose veins occur mostly in the legs, when malfunctioning valves let blood pool in veins near the skin. Causes include hereditary valve and vein wall weakness and internal or external pressure on veins. Varices are common in pregnancy, suggesting that hormone abnormalities play a role. Symptoms include a heavy feeling, with leg cramps and swelling after standing a long time. Complications include skin ulcers and thrombosis. Treatment involves strong support hose, injection therapy, or surgery. Varices in the esophagus, which often occur in liver disease, can ulcerate and bleed. Seealso hemorrhoid.

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The Blood-vein, (Timandra comae) is a moth of the family Geometridae. It has a scattered distribution in Westenr and Central Europe north of the Alps. In the British Isles the distribution is patchy outside southern England and Wales. In far eastern Europe – east opf a line running roughly from Finland through Estonia –, it is replaced by its sister species Timandra griseata. The species were split in 1931, only to be subsequently re-merged by most authors. But since 1994, new research has come out in favor of treating them as distinct species.

The wings are cream-coloured with bold red or purple fascia forming a diagonal stripe across forewings and hindwings. All wings are fringed with the same colour. The tornus of the hindwing is sharply angled giving a distinctive shape. The wingspan is 30-35 mm. Two broods are produced each year with the adults flying in May and June and again in August and September . It flies at night and is attracted to light.

The larva is grey-brown with darker spots on the back. In the UK, it feeds on the leaves of a variety of plants including dock, knotgrass, sorrel and various species of Atriplex. It overwinters as a larva.

1. The flight season refers to the British Isles. This varies in other parts of the range.

References

Chinery, Michael Collins Guide to the Insects of Britain and Western Europe 1986 (Reprinted 1991)

Skinner, Bernard Colour Identification Guide to Moths of the British Isles 1984