is an extraordinary organ that supplies blood and oxygen to all parts of the body. It is about the size of a clenched fist, weighs about 10.5 ounces, and is shaped like a cone.
The heart is divided by a partition or septum into two halves. The halves are in turn divided into chambers. The upper two chambers of the heart are called atria and the lower two chambers are called ventricles. Valves allow blood to flow in one direction between the chambers of the heart.
To learn more about the heart before taking the quiz, visit the Heart Anatomy
, Phases of the Cardiac Cycle
, and Four Steps of Cardiac Conduction