The rhythm of the normal human heart.
Blood flow occurs only when there's a difference in pressure across the valves, which causes them to open. Under normal conditions, the valves permit blood to flow in only one direction. The heart pumps blood to the lungs and to all the body's tissues by a sequence of highly organized contractions of the four chambers.
For the heart to function properly, the four chambers must beat in an organized way. The heart beat contraction begins when an electrical impulse from the sinoatrial node also called the SA node or sinus node moves through it. The SA node is sometimes referred to as the heart's "natural pacemaker" because it initiates impulses for the heartbeat.
The normal electrical sequence begins in the right atrium and spreads throughout the atria to the atrioventricular AV node. From the AV node, electrical impulses travel down a group of specialized fibers called the His-Purkinje system to all parts of the ventricles. This exact route must be followed for the heart to pump properly. As long as the electrical impulse is transmitted normally, the heart pumps and beats at a regular pace. In an adult, a normal heart beats 60 to times a minute. Arrhythmias are abnormal beats.
The term "arrhythmia" refers to any change from the normal sequence of electrical impulses, causing abnormal heart rhythms. Arrhythmias may be completely harmless or life-threatening.
What are the symptoms of abnormal heart rhythms?
Some arrhythmias are so brief for example, a temporary pause or premature beat that the overall heart rate or rhythm isn't greatly affected. But if arrhythmias last longer, they may cause the heart rate to be too slow or too fast or the heart rhythm to be erratic — so the heart pumps less effectively. The link provided below is for convenience only, and is not an endorsement of either the linked-to entity or any product or service. Each day the average heart beats expands and contracts , times and pumps about 2, gallons of blood through the body. In a year lifetime, an average human heart beats more than 2.
To understand how the heart pumps, learn about: Structure of the heart Watch an animation of heart valve anatomy The heart: Two upper chambers are called atria one is called an atrium.
Two lower chambers are called ventricles. The four heart valves are: Tricuspid valve, located between the right atrium and right ventricle Pulmonary or pulmonic valve, between the right ventricle and the pulmonary artery Mitral valve, between the left atrium and left ventricle Aortic valve, between the left ventricle and the aorta Each valve has a set of flaps also called leaflets or cusps. Each time a section of the heart contracts, it forces blood from one point to another.
It goes like this:. What exactly keeps the pace? Since your heart is your body's engine , it makes sense that it might work something like the engine in your car: It starts with a spark. How Your Heart Works.
The rhythm of the normal human heart.
What determines the rhythm of your heart? See more pictures of the heart. When blood returns to the heart from the rest of the body, it flows into the right atrium 1. The blood has been supplying oxygen throughout the body and needs a refill. The right atrium fills with this blood, which then flows into the right ventricle 2 , as well.
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The right ventricle is going to send the blood into the lungs for an oxygen fill-up. To get as much blood into the right ventricle as possible, the right atrium contracts, pushing all of the blood down into the ventricle.