Final answer:
A heartbeat, in the context of the given options, is better described as a pulse, which is the sensation of the heartbeat as felt through the walls of arteries. The pulse represents the heart rate and rhythm, which are vital signs of cardiac function and overall health.
Step-by-step explanation:
When you have a heartbeat, it is commonly referred to as a pulse. The pulse is the alternating expansion and recoil of an artery as blood is pumped through it by the heart. It is an indicator of heart rate and can be palpated manually or measured electronically. Your pulse gives important information about your health, reflecting the rate and rhythm of your heartbeats. A normal, rhythmic beating of the heart is known as sinus rhythm, which reflects a steady pace of contractions governed by the electrical signals from the pacemaker cells in the heart.
If a person's pulse is too fast, above 100 beats per minute in adults, it is known as tachycardia. If it is too slow, below 60 beats per minute, it is called bradycardia. Some heart arrhythmias, which are abnormal heart rhythms, can be life-threatening and might require interventions such as the use of a cardiac defibrillator to restore normal rhythm.