Chapter 12 cardiovascular physiology: circulatory system ~ cardiovascular system; includes pump (heart), set of interconnected tissue containing water, solutes, and cells that fills tubes (blood) Iron ~ element in which oxygen binds on hemoglobin molecule within erythrocyte: small amounts are lost from body via urine, feces, sweat, and cells sloughed from skin. Blood flow: bulk flow ~ rapid flow of blood throughout body is produced by pressures created by pumping action of heart. Inferior vena cava ~ collects blood from below heart: superior vena cava ~ collects blood from above heart, portal system ~ type of circulation characterized by 2 capillary beds connected by veins called portal veins. Innervation: blood supply, coronary arteries ~ arteries supplying myocardium, coronary blood flow ~ blood flowing through coronary arteries. 12. 4 heartbeat coordination: sinoatrial (sa) node ~ located in right atrium containing specialized cardiac muscle cells that depolarize spontaneously faster than other cells in conducting system; determines heart rate.