Does coronary veins have carbon dioxide?

Answer 1

The coronary system is comprised of arteries, arterioles, capillaries, venules and veins. From the innumerable cardiac capillaries, blood flows back to the cardiac chambers through venules, which in turn coalesce into the cardiac veins. Most cardiac veins collect and return blood to the right atrium through the coronary sinus; there may or not be a Thebesian valve covering the ostium of the coronary sinus. The major venous vessels of the human heart are: coronary sinus, the anterior interventricular veins, left marginal veins, posterior veins of the left ventricle, and the posterior interventricular veins (see also the Coronary System Tutorial).