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.
Right atrium. The right atrium is one of the four chambers of the heart. The heart is comprised of two atria and two ventricles. Blood enters the heart through the two atria and exits through the two ventricles. Deoxygenated blood enters the right atrium through the inferior and superior vena cava. The right side of the heart then pumps this deoxygenated blood into the pulmonary veins around the lungs.