Duration of the Cardiac Cycle

Our heart is the most delicate and vital organ that keeps us functioning. This muscular organ is just the size of an average fist. It is the main regulator of the cardiovascular system of the body. You must already know the basics of how it pumps blood connecting with a set of veins and arteries. The process is known to be the cardiac cycle that involves pulmonary and systemic circulation. 

Cardiac cycle overview

The cardiovascular cycle refers to the working of the person’s heart, beginning from one heartbeat till starting of the next one. Mainly it comprises two duration: 

Diastole: In this period, heart muscles tend to relax and refill the blood. 

Systole: After diastole, the period begins where blood contracts and pumps. 

Once the heart gets empty, it relaxes and expands quickly to receive the next blood influx that returns from other parts of the body. Then, again the process of contracting blood to pump to other body systems as lungs continue. Note that throughout the duration of the cardiac cycle, a healthy heart fully expands before pumping. 

Cardiac cycle processes

On average, a healthy heart beats at a rate of 70-75 beats/minute, and each heartbeat takes up to 0.8 sec to complete a cycle. The heart has two ventricles and two atrial chambers. These chambers are paired as the right heart and the left heart. 

Here, the right atrium is paired with the right ventricle, and the left atrium is paired with the left ventricle. Also, they function in sync to get the cardiac cycle going continuously. At the early stage of the cycle at the time of ventricular diastole, the heart expands and relaxes while receiving blood in the ventricles via atriums on both sides. 

Further, at the later stage of ventricular diastole, contraction takes place on the two atria, and either atrium tends to pump the blood into the below-located ventricle. At the time of ventricular systole, the ventricles contract and eject two different blood supplies through the heart. One path goes to the lungs, and the other one goes throughout other bodily systems and organs. When both atria feel relaxed, their coordination assures that the blood collects and circulates efficiently throughout the body. 

Duration of the cardiac cycle

The cardiovascular cycle consists of all kinds of physiological events that associate with a sole heartbeat. These events include mechanical events, heart sounds, and electrical events. 

The ventricle and atria tend to contract alternately with every progressive cardiac cycle. Throughout the duration of the cardiac cycle, the pressure in the chambers shifts significantly. 

Fundamentally, the cardiovascular cycle is divided into two main phases: the diastole phase, also known as the relaxation phase, and the systole phase, known as the contraction phase. Further both of these into ventricular and atrial components: 

Here are the stages involved in the cardiovascular cycle in terms of duration:

1. Atrial systole: This stage lasts within around 0.1 sec, where the atria contracts and forces the blood to move inside the ventricles. 

1. Ventricular systole: The stage takes up to 0.3 sec to complete, where contraction of both ventricles takes place, and the pulmonary trunk takes the blood to the lungs and other parts of the body through the aorta. 
2. Atrial diastole: It lasts in 0.7 sec, the atria relax, and large veins fill it with blood. 

1. Ventricular diastole: This lasts around 0.5 sec. It starts prior to atrial systole, which allows the ventricles to passively fill up with blood through the atria. 

Length of cardiac cycle formula

A normal person’s heartbeat rate is 72 beats per unit minute. Thus, the length of cardiac cycle formula is determined as: 

1/72 beats/minute=.0139 minutes/beat

At a heartbeat rate of 72/min, the duration of the cardiac cycle is found to be 0.8 sec.

Conclusion

In fact, our body, brain, every organ works perfectly because the heart is efficiently doing its work. It regulates the blood flow in the body, which is of utmost importance.Our heart is the most delicate and vital organ that keeps us functioning. This muscular organ is just the size of an average fist. The duration of the cardiac cycle plays a vital role in determining whether the heart is healthy.Human heart completes one cardiac cycle in 0.8 sec. Hence, ensure to note the formula to calculate the length of the cardiac cycle as mentioned above. The article has also covered all the processes that involve the cardiovascular system in the body. You can learn about different cardiac cycle stages, the phases within those stages, and many more details here.