How do arteries and veins get oxygen?
"Lumen" is a broad term, it indicates the arterial and venous compartments/tissues, compartments have other elements to them i.e. cells that create the blood vessel walls as well as red blood cells and other material circulating with blood itself (within the Lumen of course), so in truth, oxygen is everywhere. If you had free oxygen in your vessels then you'd have embolism, and that would mean that the "oxygen bubble" would block circulation just like a clot, which may indeed mean that you are at risk of necrosis by hypoxia. This applies to all gaseous bubbles not just oxygen, there's just no way they'd be free to move without causing harm, therefore you need the help of enzymes (i.e. intracellularly) to produce oxygen in a safe environment or some chelating minerals that are as an example contained in both myoglobin (muscles) and Hb (Lumen) to carry oxygen safely.
Veins do not need much oxygen since they are composed of elastic tissue and lesser of muscular tissue. Arteries do need oxygen since they have more muscles. There are tiny vessels and nerves dedicated to function in the vessel walls. Here is a note from google to make this very clear for you. The vasa vasorum are found in large vein and arteries such as the aorta and its branches. These small vessels serve to provide blood supply and nourishment for tunica adventitia and outer parts of tunica media of large vessels
This applies to all gaseous bubbles not just oxygen, there's just no way they'd be free to move without causing harm, therefore you need the help of enzym
yes i know that...but what about the veins they don't have any free o2 in their lumen?
Gas exchange in the lungs.
through the blood that carries Hb and a little bit of the free O2
Shorty back up
you breath in and out
Its not true that veins dont have any 02 in their lumens at all, 100 percent of oxygen is not extracted in the capillaries, however, the capillaries that service the venous tissue have 02. 02 does NOT diffuse out of the veins or the arteries, the walls are too thick, gas exchange is in the capillaries which go to every cell in the body, that is where the cells get their oxygen from.