The circulation of the body, begins in the left ventricle. From the left ventricle, blood travels through the aorta to reach various tissues and organs of the body, such as the liver, kidneys, skull and brain, stomach and intestines, and subcutaneous. After reaching the capillaries of each tissue, it undergoes tissue metabolism, consuming oxygen, absorbing carbon dioxide, and carrying away a series of waste products produced by metabolism. It returns to the right atrium via the superior and inferior vena cava to complete the body circulation. The blood in the right atrium reaches the right ventricle and begins the pulmonary circulation. From the right ventricle, blood reaches the pulmonary artery, where it undergoes gas exchange within the air bubbles, releasing carbon dioxide and taking in oxygen from the alveoli, reaching the pulmonary veins and eventually the left atrium, completing the pulmonary circulation.