Module 8 circulatory system i: the heart. Four principal functions of the cardiovascular system: transports oxygen/nutrients to all cells, transports co2/waste products from cells, helps regulate body temperature and ph, transports/distributes hormones and other substances within body. Left atrium/ventricle pumps blood to rest of body: wall of the left ventricle much thicker than wall of right ventricle. The left ventricle must contract more forcefully to propel the blood through the entire systemic circulation: right atrium/ventricle pumps blood to lungs. Left atrioventricular (av) valve = bicuspid or mitral valve. Superior vena cava: delivers blood from head/upper limbs to heart. Left ventricle: pumps blood into aorta, which then distributes the blood to body: right av (tricuspid) valve, ensures: blood travels from right atrium right ventricle, prevents: backup in atrium when ventricles contract. Left av (bicuspid) valve: ensures: blood travels from left atrium left ventricle, prevents: backup in atrium when ventricles contract.