What term describes the contraction of heart muscle?

The term that describes the contraction of heart muscle is "systole." During systole, the heart muscles contract to pump blood out of the chambers of the heart and into the arteries. This phase is critical for maintaining blood circulation throughout the body, allowing oxygen-rich blood to reach various tissues and organs.

In the context of heart function, systole leads to the ejection of blood from the ventricles—specifically, the left ventricle pumps oxygenated blood into the aorta, while the right ventricle sends deoxygenated blood into the pulmonary artery. The contraction during systole follows relaxation of the heart (diastole) and is a key part of the cardiac cycle, which includes both contraction and relaxation phases. This rhythmic process maintains efficient blood flow and is essential for overall cardiovascular health.

The other terms mentioned relate to different aspects of heart function: diastole refers to the relaxation phase when the chambers fill with blood, the cardiac cycle encompasses the entire sequence of contraction and relaxation, and atrial fibrillation denotes an irregular heartbeat caused by chaotic electrical signals in the atria, rather than a specific phase of muscle contraction.