Which part of the ECG represents electrical impulse transmission through the ventricles?
OverviewWhat is the conduction system of the heart?Your heart’s conduction system is the network of nodes (groups of cells that can be either nerve or muscle tissue), specialized cells and electrical signals that keep your heart beating. Show
Two types of cells control your heartbeat:
Your heart (cardiac) conduction system sends the signal to start a heartbeat. It also sends signals that tell different parts of your heart to relax and contract (squeeze). This process of contracting and relaxing controls blood flow through your heart and to the rest of your body. FunctionWhat are the steps of the heart conduction pathway?Your heart is a pump that sends blood through your body. For each heartbeat, electrical signals travel through the conduction pathway of your heart. It starts when your sinoatrial (SA) node creates an excitation signal. This electrical signal is like electricity traveling through wires to an appliance in your home. The excitation signal travels to:
These steps make up one full contraction of your heart muscle. Your heart conduction system sends out thousands of signals per day to keep your heart beating. How does electrical conduction perform with the rest of your heart?The electrical signals that travel through your heart conduction system cause your heart to expand and contract. These contractions control how blood flows through your heart. Ideally, the electrical conduction system keeps up a steady, even heart rate. It also helps your heart speed up when you need more blood and oxygen or slow down when it’s time to rest. Anatomy What are the parts of the cardiac conduction system?Your cardiac conduction system contains specialized cells and nodes that control your heartbeat. These are the:
Sinoatrial node Your sinoatrial node is sometimes called your heart’s natural pacemaker. It sends the electrical impulses that start the heartbeat. The SA node is in the upper part of your heart’s right atrium. It is at the edge of your atrium near your superior vena cava (vein that brings oxygen-poor blood from your body to your heart). Your autonomic nervous system controls how fast or slowly your SA node sends electrical signals. This part of the nervous system directs hormones that control your heart rate based on what you are doing. For example, your heart rate increases during exercise and slows when you are asleep. The autonomous nervous system includes your:
Atrioventricular node The atrioventricular node delays the SA node’s electrical signal. It delays the signal by a consistent amount of time (a fraction of a second) each time. The delay ensures that your atria are empty of blood before the contraction stops. The atria are the heart’s upper chambers. They receive blood from your body and empty it into the ventricles. Your AV node is located in an area known as the triangle of Koch (located between the septal leaflet of the tricuspid valve, the coronary sinus and the membranous portion of the interatrial septum). This is near the central area of the heart. Bundle of His The bundle of His is also called the atrioventricular bundle. It is a branch of fibers (nerve cells) that extends from your AV node. This fiber bundle receives the electrical signal from the AV node and carries it to the Purkinje fibers. The bundle of His runs down the length of the interventricular septum, the structure that separates your right and left ventricles. The bundle of His has two branches:
Purkinje fibers The Purkinje fibers are branches of specialized nerve cells. They send electrical signals very quickly to your right and left heart ventricles. Your Purkinje fibers are in the subendocardial surface of your ventricle walls. The subendocardial surface is part of the endocardium, the inner layer of tissue that lines your heart’s chambers. When the Purkinje fibers deliver electrical signals to your ventricles, the ventricles contract. As they contract, blood flows from your right ventricle to your pulmonary arteries and from your left ventricle to your aorta. The aorta is the body’s largest artery. It sends blood from your heart to the rest of your body. Frequently Asked QuestionsWhat else should I ask my doctor?You may want to ask your healthcare provider:
A note from Cleveland Clinic Your heart’s conduction system is the network of signals that keeps your heart beating. These electrical signals make your heart contract or relax. Each contraction also controls blood flow through your heart. You can keep your heart conduction system and your entire heart healthy by making lifestyle changes such as managing stress and exercising regularly. Which part of the ECG represents electrical impulse through the ventricles?The QRS complex is a record of the movement of electrical impulses through the lower heart chambers (ventricles). The ST segment shows when the ventricle is contracting but no electricity is flowing through it. The ST segment usually appears as a straight, level line between the QRS complex and the T wave.
What do the P QRS and T waves represent?The P wave in an ECG complex indicates atrial depolarization. The QRS is responsible for ventricular depolarization and the T wave is ventricular repolarization.
What does the R wave represent?the R wave reflects depolarization of the main mass of the ventricles –hence it is the largest wave. the S wave signifies the final depolarization of the ventricles, at the base of the heart.
Which waves on an ECG are produced in the ventricles?The wave of depolarization spreads through the ventricles predominantly from the endocardial area to the epicardium. The initial 0.01 second of the QRS complex is caused by depolarization of the middle of the left side of the interventricular septum.
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