The human heart circulates blood throughout the body like a pump. It is a muscle in the centre of your chest that is slightly slanted to the left and is around the size of your fist. Your heart beats about 100,000 times a day. Through a system of blood vessels known as arteries and veins, your circulatory system continuously circulates around 5 litres (8 pints) of blood throughout your body. This blood helps your muscles and organs function properly by supplying oxygen and nutrients to every region of your body. Waste materials and unnecessary carbon dioxide are also removed by your blood. Let’s know what actually keeps your heart beating and in which phases the cardiac cycle takes place.
Also Read: Understanding The Benefits And Risks Of A Temporary Pacemaker
Structure of the Heart
There are four key sections of the heart:Heart Chambers:
There are left and right sides of your heart. The septum, a thin muscle wall, separates them. There is an upper chamber and a lower chamber on either side. The left and right atriums, also known as the atria, are the two upper chambers that receive blood streaming into the heart, while the left and right ventricles, also known as the ventricles, are the two bottom chambers that pump blood out of the heart.The Heart's Layers:
Three layers of muscle make up your heart. The thin outer layer that envelops and shields your heart is called the pericardium. The heart's endocardium is a thin inner layer that lines the four chambers and the valves, while the myocardium is a strong, muscular middle layer that contracts and relaxes to pump blood out of the heart to the rest of your body.Heart Valves:
Like a one-way highway, your blood only flows in one direction around your heart and the rest of your body. Your heart's valves regulate which way blood flows. With each heartbeat, they function as doors that open and close. Heart valves may be referred to as leaflets or cusps. In your heart, there are four valves. Between the right atrium and the right ventricle is the tricuspid valve. It stops blood from returning to the right atrium during contractions of the right ventricle. The pulmonary valve lies between the pulmonary artery and the right ventricle. It stops blood from returning to the right ventricle after being pushed to the lungs. The left atrium and left ventricle are separated by the mitral valve. When the left ventricle contracts, it stops blood from returning to the left atrium. The left ventricle and the aorta are separated by the aortic valve. After blood has been pushed to the aorta to travel to the rest of the body, it stops it from returning to the left ventricle.Coronary Arteries:
Your heart muscle receives oxygen-rich blood from your coronary arteries. They split off from your body's major artery, the aorta. Coronary artery disease, sometimes called coronary heart disease, is caused by fatty material in the walls of your coronary arteries narrowing them. A blood clot, or collection of blood, forms around any broken fatty material in an attempt to restore the damaged artery wall. Your coronary artery may become blocked by this clot, depriving your heart muscle of oxygen and blood, resulting in a heart attack.Also Read: Heat Stroke: Symptoms, Treatments, And Prevention Tips
What is a Cardiac Cycle?
The mechanical, electrical, and acoustic activities that take place in the heart and major arteries are described and related sequentially by the cardiac cycle. Typically, the cardiac cycle is explained from the beginning of heart muscle contraction to the relaxation. This results in pumping of oxygenated blood throughout the body and deoxygenated blood to lungs.The electrical system that powers your heart begins with the sinoatrial (SA) node, also known as the heart's natural pacemaker. The SA node, which is found in the heart's upper right chamber, generates electrical signals that force the heart's muscles to contract. The cardiac cycle, which pumps blood throughout the body via the heart, starts with this procedure. The atria, or higher chambers, get the signal first, contract, and force blood into the ventricles, or lower chambers. It then travels to the atrioventricular (AV) node, which permits the ventricles to fill with blood by slightly slowing the signal.
The ventricles contract as a result of the signal's final propagation, pumping blood to your lungs and the rest of your body. Every pulse repeats this repetitive process, which keeps you alive and in good health.
What are the Phases of the Cardiac Cycle?
| Phase | Function |
| Atrial diastole | Blood filling in atria Opening of atrioventricular valves |
| Atrial systole | Contraction of atria Active filling of ventricles |
| Ventricular diastole | First third of the diastolic phase (early ventricular diastole): ventricular rapid inflow Middle third of the diastolic phase (late ventricular diastole): passive inflow or diastasis Last third of the diastolic phase (atrial diastole): ventricular filling due to atrial contraction (20%) |
| Ventricular systole | Contraction of ventricles Semilunar valve opens (opening of valves of aorta and pulmonary vein) Ventricle emptying |
Diseases Associated with Abnormal Cardiac Cycle
The circulatory system and heart can malfunction sometimes. Heart and circulatory disorders, commonly known as cardiovascular disorders, may result from this. Numerous circulation and heart conditions exist, such as:- Coronary Heart Disease
- Angina
- Heart Attack
- Cardiac Arrest
- Congenital Heart Disease
- Arrhythmias
- Inherited Heart Conditions
- Stroke
- Type 2 Diabetes
- Vascular Dementia
Conclusion
Your heart is the pump that keeps you alive by enabling blood and oxygen to circulate throughout your body. There are four chambers and four valves in the heart. Blood is pumped out of the bottom two chambers (ventricles) and received by the upper two (atria). The valves close to prevent blood from flowing backward and open to let blood pass through. All of this takes place in a single heartbeat. Learn what keeps your heart beating with a detailed overview of the phases of the cardiac cycle. Explore how your heart works to pump blood effectively with Asian Hospital, the Best Cardiac Hospital in Mumbai. For expert insight, book your consultation now!FAQs
Q1: Why is understanding the cardiac cycle important?A: Understanding the cardiac cycle helps explain how your heart works and why maintaining a healthy lifestyle is crucial for efficient blood circulation and overall health.
Q2: What tests evaluate the cardiac cycle?
A: Tests like an electrocardiogram (ECG), echocardiogram, and stress tests can help assess the heart’s electrical activity and blood flow during the cardiac cycle.
Q3: What happens if the cardiac cycle is disrupted?
A: Disruptions in the cardiac cycle, such as arrhythmias (irregular heartbeats), can affect the heart’s ability to pump blood effectively. This may lead to symptoms like fatigue, shortness of breath, or more serious complications if untreated.
