Define heart rate.

• A. The volume of blood pumped out by the heart per beat.
• B. The total blood volume in the body.
• C. The number of heart beats per minute.
• D. The amount of blood pumped per minute.

Answer: (C)

Heart rate is how many times the heart beats in a given time, usually per minute. It’s measured in beats per minute (bpm). This is different from stroke volume, which is the amount of blood ejected with each beat, and from cardiac output, which is the total amount of blood pumped per minute (heart rate multiplied by stroke volume). Total blood volume is the entire blood present in the circulatory system and isn’t about how fast the heart beats. At rest, a typical heart rate is about 60–100 bpm, and it rises with exercise or stress due to autonomic regulation.