So we'll begin with a drop of blood somewhere in the body. The blood gives nutrients and oxygen to a cell and takes carbon dioxide and wastes. Then the blood goes through capillaries (tiny blood vessels) and into veins. The veins lead to either the superior vena cava or inferior cena cava, depending on what part of the body it came from. Then it travels to the right atrium and into the right ventricle. The blood then goes through the pulmonary artery, through a capillary, and into an aveolus (an air sac in the lung, plural aveoli). There, it gets rid of its waste and collects nutrients and oxygen. It goes back through a capillary, through the pulmonary vein, and into the left atrium. It travels to the left ventricle and out of the heart through the aorta. It then goes through an artery to another part of the body. It goes through a capillary and to the cell and gives the cell the nutrients and takes the wastes. The cycle repeats.
