Organ That Pumps Blood. The upper chambers of the heart are small in size and have thin muscular walls, they are known as auricles of atria. While searching our database we found 1 possible answer for the crossword clue:

The organs of the circulatory system are the heart, arteries, veins and capillaries. The human circulatory system is responsible for the transport of materials inside the human body. The heart is a hollow muscular organ that pumps blood through blood vessels to various parts of the body by repeated rythamatic contractions.