Each beat of human heart is completed in?

Appeared in: HPSSC - 2015

Explanation

The question asks for the time taken to complete one heartbeat, which is the duration of the cardiac cycle.
A normal resting heart rate for an adult is between 60 and 100 beats per minute. A commonly used average is 75 beats per minute.
To calculate the duration of one beat, you divide 60 seconds by the heart rate. For a rate of 75 bpm, this is 60 / 75 = 0.8 seconds.
This 0.8-second cycle is composed of atrial systole (0.1s), ventricular systole (0.3s), and complete cardiac diastole (0.4s).

Option A: A duration of 5.8 seconds per beat would correspond to a heart rate of approximately 10 beats per minute (60 / 5.8), which is a life-threateningly low rate (severe bradycardia) and not the duration of a normal heartbeat.
Option B: A duration of 8.5 seconds per beat equates to a heart rate of about 7 beats per minute (60 / 8.5). This is an extremely slow and fatal heart rate, far from the normal physiological range.
Option D: A duration of 85 seconds per beat would mean a heart rate of less than 1 beat per minute (60 / 85 ≈ 0.7 bpm). This is incompatible with life.

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.
Understanding the normal duration of the cardiac cycle is fundamental for nurses to interpret heart rates and rhythms correctly.
Abnormalities in the cardiac cycle duration indicate conditions like tachycardia (cycle shorter than 0.6 seconds, rate >100 bpm) or bradycardia (cycle longer than 1.0 second, rate <60 bpm).
Nurses must assess for signs of compromised cardiac output in patients with very fast or slow heart rates, such as dizziness, shortness of breath, or chest pain.

How to Approach the Question

First, identify the core concept of the question, which is the duration of a single heartbeat or 'cardiac cycle'.
Recall the normal resting heart rate for an adult, which is typically around 60-100 beats per minute. A common average used for calculations is 72-75 bpm.
Use the formula: Cardiac Cycle Duration = 60 seconds / Heart Rate (in bpm).
Calculate the duration: 60 seconds / 75 beats = 0.8 seconds.
Compare this calculated value with the given options to find the correct answer.
Eliminate other options by recognizing they represent physiologically impossible heart rates (either extremely slow or fast).

Concept Tested & Keywords

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Practise the full HPSSC - 2015

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