Chapter 19 - Section 19.5 - Study Guide - Assess Your Learning Outcomes - Page 740: 6

The duration of atrial systole, ventricular systole, and the quiescent period can vary among individuals and depending on heart rate, but typical values are as follows: - **Atrial Systole:** Approximately 0.1 seconds (100 milliseconds) - **Ventricular Systole:** Approximately 0.3 seconds (300 milliseconds) - **Quiescent Period (Isovolumetric Relaxation):** Approximately 0.4 seconds (400 milliseconds) To calculate heart rate (HR) from these values, you can use the following formula: **Heart Rate (beats per minute) = 60 / Cardiac Cycle Time** The cardiac cycle time is the sum of the durations of atrial systole, ventricular systole, and the quiescent period. For example, if we use the typical values mentioned above: - Cardiac Cycle Time = Atrial Systole + Ventricular Systole + Quiescent Period = 0.1 seconds + 0.3 seconds + 0.4 seconds = 0.8 seconds Then, the heart rate would be: - Heart Rate = 60 / 0.8 = 75 beats per minute Please note that these values are approximate and can vary based on individual factors, health conditions, and heart rate variability. In clinical practice, heart rate is often calculated using the R-R interval on an electrocardiogram (ECG) to account for potential irregularities in the heart rate.

The duration of atrial systole, ventricular systole, and the quiescent period can vary among individuals and depending on heart rate, but typical values are as follows: - **Atrial Systole:** Approximately 0.1 seconds (100 milliseconds) - **Ventricular Systole:** Approximately 0.3 seconds (300 milliseconds) - **Quiescent Period (Isovolumetric Relaxation):** Approximately 0.4 seconds (400 milliseconds) To calculate heart rate (HR) from these values, you can use the following formula: **Heart Rate (beats per minute) = 60 / Cardiac Cycle Time** The cardiac cycle time is the sum of the durations of atrial systole, ventricular systole, and the quiescent period. For example, if we use the typical values mentioned above: - Cardiac Cycle Time = Atrial Systole + Ventricular Systole + Quiescent Period = 0.1 seconds + 0.3 seconds + 0.4 seconds = 0.8 seconds Then, the heart rate would be: - Heart Rate = 60 / 0.8 = 75 beats per minute Please note that these values are approximate and can vary based on individual factors, health conditions, and heart rate variability. In clinical practice, heart rate is often calculated using the R-R interval on an electrocardiogram (ECG) to account for potential irregularities in the heart rate.