Trace a drop of blood from the left atrium to the left hallux and back to the right atrium

The Blood moves in the heart through two large veins, the inferior and superior vena cava, and exhausting oxygen-poor blood from the body into the right atrium. The pulmonary vein discharges oxygen-rich blood, from the lungs into the left atrium.

unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.