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.
If you look inside the right atrium, you could see a big blue blood vessel that opens up into it from the top and another that approaches from the bottom. The right atrium receives blood from both of these inferior and superior vena cavaâs (vein=towards the heart, cava=big). The superior vena cava brings in all the blood from the upper half of the body. Okay so we have blood dumping into the right atrium. The blood falls down with gravity from the right atrium and into this particular passage way, down into this right ventricle. This is bigger than the right atrium and has a thicker muscle wall because the right ventricle does stronger pumping.