In the circulatory system a vein is a type of blood vessel that carries blood back from the various organs and parts of the body to the heart and lungs in order to be purified and pumped back to the various organs and parts of the body once again. The thick outer layer of the veins are made up of collagen and are wound in smooth muscle and the interior of these veins are lined with endothelial cells called initma. Veins are often visible through the skin, sometimes because they bulge, and at other times because the skin is extremely pale and thin,
Bulging veins is not necessarily an indication of any problem, and they usually do not look unpleasant either. If you are worried about the veins bulging, you should consult your doctor, but in all probability what you are seeing is normal, and you are being too critical of yourself. Even if this is a recent development, it is only because your body is still undergoing many changes. Many adults have veins that bulge or are otherwise visible through the skin, and this almost never happens during childhood, which is why you have never noticed them before.
Since you are young the possibility of these veins bulging because of being varicose veins are not likely. A more logical reason could be because of the fact that you may be under weight and that is why they seem to stick out in an abnormal way. The best way to remedy this is to put on weight. There is probably nothing you can do about this either - during adolescence many people tend to be rather thin, but they usually start to fill out once they cross 20. If the problem still bothers you consult your doctor for a further diagnosis.
answered by G M