Inductive definition of CW complexes. If the largest dimension of any of the cells is n, then the CW complex is said to have dimension n. If there is no bound to the cell dimensions then it is said to be infinite-dimensional. The n-skeleton of a CW complex is the union of the cells whose dimension is at most n.
Deoxygenated blood enters the right atrium through three major veins: the superior and inferior vena cava and the coronary sinus. The superior vena cava returns all of the blood to the heart from tissues superior to the heart in the head, neck, arms and upper thorax.
The coronary arteries supply blood to the heart muscle itself. The right coronary artery is the major artery that supplies blood to the upper and lower chambers on the right side of the heart. There is also a left coronary artery. Watch this animation to learn more about these arteries.