How much time does a heartbeat last?

Appeared in: MP NHM CHO-2024 (Shift-2)

Explanation

A single heartbeat is also known as one complete cardiac cycle.
The duration of the cardiac cycle is inversely related to the heart rate.
Assuming a normal resting heart rate of 75 beats per minute (bpm) for a healthy adult, the duration of one beat is calculated as 60 seconds / 75 bpm = 0.8 seconds.
This cycle includes both the contraction phase (systole) and the relaxation phase (diastole).

Option A: A duration of 2 seconds per heartbeat corresponds to a heart rate of 30 beats per minute (60/2), which is a sign of severe bradycardia (an abnormally slow heart rate), not a normal resting state.
Option C: A duration of 0.5 seconds per heartbeat corresponds to a heart rate of 120 beats per minute (60/0.5). This is considered tachycardia (an abnormally fast heart rate) for a person at rest.
Option D: A duration of 1.5 seconds per heartbeat corresponds to a heart rate of 40 beats per minute (60/1.5). This is considered bradycardia (a slow heart rate) and is outside the normal resting range for most adults.

Visual 1: Diagram - A diagram of the cardiac cycle showing the three phases (atrial systole, ventricular systole, complete diastole) with their respective durations (0.1s, 0.3s, 0.4s) and corresponding ECG waves (P wave, QRS complex, T wave). This visual helps connect the timing to the electrical and mechanical events of the heart.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Duration of the Cardiac Cycle as background academic context rather than a clinical decision trigger.
Assessing heart rate is a fundamental nursing skill. The rate determines the duration of each cardiac cycle and is a key indicator of a patient's cardiovascular status.
Deviations from the normal duration indicate tachycardia (fast rate, short cycle) or bradycardia (slow rate, long cycle), which can decrease cardiac output and tissue perfusion, requiring nursing assessment and potential intervention.
What if? If the patient is a highly conditioned athlete, their resting heart rate might be as low as 40-50 bpm. In this case, the duration of their heartbeat would be longer (1.2 to 1.5 seconds), which is a normal physiological adaptation for them and not necessarily a sign of disease.

How to Approach the Question

This is a factual recall question about a standard physiological value.
First, recall the normal range for a resting heart rate in an adult, which is 60-100 beats per minute (bpm).
Recognize that a commonly used average for calculations is around 75 bpm.
Use the formula: Duration of one beat (in seconds) = 60 seconds / Heart Rate (in bpm).
Calculate the duration: 60 / 75 = 0.8 seconds.
Compare this calculated value to the given options to find the correct answer.

Concept Tested & Keywords

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Practise the full MP NHM CHO-2024 (Shift-2)

Attempt every question from this paper in a timed mock, then review the full solution for each one.