Video Transcript
Which of the following best defines the term heart rate, bpm? (A) The volume of blood the heart releases per second. (B) The number of times the heart beats per minute. (C) The number of times the heart stops per minute. (D) The volume of blood the heart releases per minute. Or (E) the number of times the heart beats per hour.
As we all know, the heart has one vitally important job to do, and that is to
beat. Each heartbeat can be split into two phases. The first is where the cardiac muscle of the heart relaxes to allow blood to enter,
and the second is where the cardiac muscle contracts to pump the blood back out of
the heart. Blood leaving the heart either travels to the lungs, where it will release carbon
dioxide and take up oxygen, or to the rest of the body, where it will deliver oxygen
to respiring tissues.
A human heart beats about 100,000 times a day, releasing around 6,000 liters of
blood. That’s more liters of blood pumped through you in a day than liters of fuel an
average person will put in their car in a whole year. This question is asking us about heart rate. A rate tells us how often a particular event occurs in a given amount of time, in
other words how frequently it happens. So heart rate tells us the number of times the heart beats in a given amount of
time. We can therefore rule out answer options (A) and (D), because they both refer to the
volume of blood the heart releases in a given amount of time rather than how many
times it beats.
We can also rule out answer option (C), because it refers to the number of times the
heart stops. In actual fact, if our heart stopped, we would most likely die within a matter of
minutes.
We are left with answer options (B) and (E), both of which are valid definitions for
heart rate because they both describe the number of times the heart beats in a given
amount of time. But only one of them gives the correct unit of time based on the units for heart rate
given in the question, bpm.
bpm stands for beats per minute, and it’s the way heart rate is most commonly
expressed. Heart rate is an important measurement because it indicates how well the heart is
working and can be used to help diagnose a range of heart conditions. We have therefore determined that the correct answer is (B). The best definition for heart rate, bpm, is the number of times the heart beats per
minute.
