RT Book, Section A1 Awoniyi, Caleb A. A2 Freeman, Brian S. A2 Berger, Jeffrey S. SR Print(0) ID 1102569634 T1 Cardiac Anatomy T2 Anesthesiology Core Review: Part One Basic Exam YR 2014 FD 2014 PB McGraw-Hill Education PP New York, NY SN 9780071821377 LK accessanesthesiology.mhmedical.com/content.aspx?aid=1102569634 RD 2024/04/19 AB In humans, blood circulates within a closed system of blood vessels. The system is said to be closed because arteries and veins are connected with each other through small vessels. This requires the action of a pump, which is provided by the heart. The heart is composed of four chambers, right atrium and ventricle, and the left atrium and ventricle. The right and left atria receive blood from the venous system and the left atrium and ventricles pumps blood into the arterial system.