![\"vena\"](\"https:\/\/www.simbex.hr\/wp-content\/uploads\/2016\/10\/vena.jpg\")
<\/p>\n<\/p>\n
The wall consists of three layers.<\/p>\n
Tunica interna \u2013 the inner layer consisting of endothelial cells.<\/p>\n
Tunica medica \u2013 the middle layer consisting of smooth muscle cells.<\/p>\n
Tunica adventitia (externa) \u2013 the outer layer consisting of connective tissue.<\/p>\n
The leg veins have venous valves in form of sails directed towards the heart, dividing the vein into segments of various length.<\/p>\n
![\"zalistak\"](\"https:\/\/www.simbex.hr\/wp-content\/uploads\/2016\/10\/zalistak.jpg\")
The venous valves open when blood is pushed upwards, in the opposite direction of The valves close right after blood has passed, preventing the backflow of blood.<\/p>\n
In the deep veins<\/strong><\/p>\n A prerequisite for the normal function of venous valves is the appropriate tone of vein walls<\/strong>. When the tone of the outer vein is reduced, the vein is enlarged\u00a0and because of that the venous valves cannot close completely. This enables reflux of blood into legs (venous insufficiency) and its flow to superficial veins, where it may clot and build an obstruction. The volume of blood the veins have to receive grows and this affects the development of varicose veins.<\/p>\n Superficial veins<\/strong><\/p>\n In the case of weakened venous valves in the superficial veins, the deep veins have to take over their function and convey larger volumes of blood, which additionally enlarges and weakens them. The enlargement prevents the venous valves to close completely, so blood travels to the heart with delay.<\/p>\n The first sign of varicose veins are heavy feeling in the legs, legs swelling or visible varicose veins under the skin. Skin changes on the legs may also appear, in that case we are talking about chronic venous insufficiency.<\/p>\n","protected":false},"excerpt":{"rendered":" The wall consists of three layers. Tunica interna \u2013 the inner layer consisting of endothelial cells. Tunica medica \u2013 the middle layer consisting of smooth muscle cells. Tunica adventitia (externa) \u2013 the outer layer consisting of connective tissue. The leg veins have venous valves in form of sails directed towards the heart, dividing the vein […]<\/p>\n","protected":false},"author":9,"featured_media":7219,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[427,429],"tags":[],"class_list":["post-12985","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-health-of-feet-and-legs","category-human-blood-circulation"],"yoast_head":"\n