Small vessels that carry deoxygenated blood back through the body to the heart.
A blood vessel which takes deoxygenated blood containing waste carbon dioxide from the tissues back to the heart.
Blood vessels that return blood from the body and the lungs to the heart. Blood returning from the body requires replenishing of its oxygen content, which was removed by the tissues. Blood is oxygenated in the lungs and then returned to the left ventricle, which pumps it into the aorta.
Blood vessels that return oxygen-depleted blood from the body to the heart.
Blood vessels that carry deoxygenated blood back to the heart. Veins complete the circulation of the blood that begins in the arteries, which transport oxygenated blood from the heart to the rest of the body. Unlike arteries, veins do not pulse; they depend on the movement of muscle surrounding them to push the blood along. Veins in the arms and legs (but not in the head, neck, or torso) have one-way valves that allow the blood to flow only in one direction.
Any of many vessels that carry blood to the heart; it may be part of the pulmonary venous system, portal system, or (most veins) the systemic venous system. All veins except the pulmonary vein carry de-oxygenated blood from the tissues of the body to the vena cava and heart. The walls of veins are thinner and less elastic than the walls of arteries and contain valves that maintain the flow of blood toward the heart.
A blood vessel conveying blood toward the heart. All veins except the pulmonary vein carry deoxygenated blood from the tissues, via the capillaries, to the vena cava. The walls of veins consist of three tissue layers, but these are much thinner and less elastic than those of arteries. Veins contain valves that assist the flow of blood back to the heart.
The vessels which return the blood to the heart after it has circulated through the tissues; they are both more numerous and more capacious than the arteries.
A vessel carrying deoxygenated (dark red) blood to the heart, except for the pulmonary veins, which carry oxygenated blood. The vein wall has three layers: an endothelial lining folded into valves, a thin smooth muscle middle layer, and a thin fibrous connective tissue outer layer. Veins differ from arteries in their larger capacity and greater number; also in their thinner walls, larger and more frequent anastomoses, and presence of valves that prevent backward circulation. The systemic veins consist of two sets, superficial or subcutaneous, and the deep veins, with frequent anastomoses between the two. The former do not usually accompany an artery, as do the latter. The systemic veins may also be considered in three groups those entering the right atrium through the superior vena cava, those through the inferior vena cava, and those through the coronary sinus.
Thin-walled blood vessels that are less elastic than arteries; veins contain cup-like valves that keep blood flowing in one direction to the heart and prevent blood from flowing backward.
The conduits that convey the vital fluid towards the organ responsible for its circulation.
A circulatory conduit responsible for transporting deoxygenated blood from diverse regions of the anatomy back to the heart.
A vein is a blood vessel responsible for carrying blood back to the heart from different organs and tissues within the body. Similar to arteries, veins possess three layers: a smooth inner lining, a middle layer containing muscle, and an outer covering composed of fibers. Nonetheless, the pressure of blood within veins is lower compared to arteries. Moreover, veins have thinner walls that are less elastic, contain less muscle, and are generally weaker when contrasted with arterial walls.
Numerous veins are lined with folds that serve as valves, responsible for directing the blood flow exclusively towards the heart. The movement of blood within the veins is facilitated by the pressure exerted on the vessel walls due to the contractions of adjacent muscles.
Strand of vascular tissue in a flat organ, often visible on the surface.
The small ribs forming the frame-work of leaves, or other organs.
The vascular tissue of the leaf.
Strands of tissue that carry water and nutrients and provide support. Collectively they constitute the vascular system of the plant.
Vascular structure in a leaf for support and transport of water and nutrients.
One of the thickened strands or lines visible in a leaf (or petal, etc), which contains the vessels or tubes that conduct water and food (as in the arteries and veins of the human body).
Any one of the strands of conducting tissue visible through the surface of a leaf or flower petal, though also used for the linear patterns on some petals designed to guide pollinating insects to the nectar. The pattern of venation of a leaf is characteristic for each plant species and is an important aid to identification. The primary vein is often called the midvein or midrib and secondary veins are alternatively called lateral veins; tertiary veins commonly form a reticulate pattern in dicotyledons, but in most monocotyledons (for example, grasses, lilies) nearly all the leaf veins lie parallel.
A strand of strengthening and conducting tissue running through a leaf or modified leaf, such as a petal. The arrangement of the veins (venation) takes one of several forms; for example, the veins may form a network (net venation) or be in a parallel (parallel venation).
A blood vessel that carries blood toward the heart.
A blood vessel that transports blood from the body’s tissues back toward the heart. Veins, similar to arteries, consist of three layers (an inner, middle, and outer layer), but they are not as thick as arterial walls. Many veins, particularly those near the surface, are equipped with valves that enable blood to flow in only one direction. With the exception of the pulmonary vein, the blood in veins is typically dark in color due to its lower oxygen content. When a vein is cut, blood seeps out, while in the case of a severed artery, blood spurts out with each heartbeat.