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A Tour of the Cardiovascular System
VOCABULARY

oxygen-depleted blood
heart
chamber
atrium
blood
lungs
heartbeat
one-way flow
bulges
strokes
What path does the blood take? Let us beginwith the oxygen-depleted blood arriving at the heart through the two large veins—the superior (top) and inferior (bottom) venae cavae. These veins empty into the first chamber of the heart, the rightatrium. The right atrium then squeezes the blood into a more muscular chamber, the right ventricle. From here the blood goes to the lungs through the pulmonary trunk and the two pulmonary arteries—theonly arteries carrying oxygen-depleted blood. This is normally done by veins.
While in the lungs, blood releases carbon dioxide and absorbs oxygen. It then flows down into the heart’s left atriumthrough the four pulmonary veins—the only veins carrying oxygen-rich blood. The left atrium empties into the heart’s most powerful chamber, the left ventricle, which pumps oxygenated blood out throughthe aorta and into the body. The two atria contract together followed by the two ventricles, the dual sequence constituting a heartbeat. Four internal valves ensure a one-way flow of blood through theheart.
Because it has to pump blood to the extremities of the body, the more muscular left ventricle has about six times the force of the right ventricle. The resulting pressure could easily causeaneurysms (bulges or dilations in arterial walls) or even potentially deadly strokes in the brain were it not for an ingenious mechanism for absorbing the pressure surges.






El circuito delsistema cardiovascular
¿Cuál es su recorrido? Empecemos con la sangre desoxigenada que llega al corazón por dos grandes venas: la cava superior y la inferior, las cuales desembocan en la aurículaderecha, la primera cavidad del corazón. Acto seguido, es impulsada al ventrículo derecho —cavidad más musculosa que la primera—, desde donde fluye a los pulmones a través del tronco pulmonar y las dos...