What is the Cardiac Cycle?
The cardiac cycle represents the series of events that occur to complete a heartbeat. The electrical impulse is started by the SA node, which causes the atria and ventricles to contract and relax. During this process, the heart muscles undergo changes, involuntarily pumping blood through the circulatory system.
During a cardiac cycle, each ventricle pumps out approximately 70 mL of blood which is called the stroke volume. The stroke volume multiplied by the heart rate gives the cardiac output. Therefore, the cardiac output can be defined as the volume of blood pumped out by each ventricle per minute and averages 5000 mL or 5 litres in a healthy individual. Each cardiac cycle consists of a complete contraction and relaxation of both the atria and ventricles and each cardiac cycle lasts approximately 0.8 seconds.
In the cardiac cycle, the heart contracts during systole, expelling blood, and relaxes during diastole, filling with blood. When the atria contract, they push blood into the ventricles through the valves, creating the “lubb” sound when the valves close. Then, the ventricles force blood into the pulmonary and systemic arteries, producing the “dubb” sound as these arteries’ valves close.
Cardiac Cycle- Phases, Diagram, and Physiology of the Cardiac Cycle
The cardiac cycle is a sequential event in the heart that is cyclically repeated. The cardiac cycle diagram shows the cardiac cycle phases consisting of systole and diastole of both the atria and ventricles. The cardiac cycle class 11 is an important concept that is also studied in higher classes.
It is regulated by electrical signals from the sinoatrial (SA) node and atrioventricular (AV) node, which ensures the circulation of oxygenated blood throughout the body. The heart beats 72 times per minute, that is many cardiac cycles are performed per minute. In this article, we will cover the cardiac cycle – steps, diagram, and physiology of the cardiac cycle.
Table of Content
- Cardiac Cycle Definition
- What is the Cardiac Cycle?
- Cardiac Cycle Diagram
- Physiology of the Cardiac Cycle
- Cardiac Cycle Phases
- Duration of the Cardiac Cycle