An electrical stimulus is generated by the sinus node also called the sinoatrial node, or SA node. This is a small mass of specialized tissue located in the right upper chamber atria of the heart. The sinus node generates an electrical stimulus regularly, 60 to times per minute under normal conditions.
The atria are then activated. The electrical stimulus travels down through the conduction pathways and causes the heart's ventricles to contract and pump out blood.
The 2 upper chambers of the heart atria are stimulated first and contract for a short period of time before the 2 lower chambers of the heart ventricles. The electrical impulse travels from the sinus node to the atrioventricular node also called AV node. The bundle of His divides into right and left pathways bundle branches to give electrical stimulation to the right and left ventricles. Normally at rest, the heart contracts about 60 to times a minute depending on your age.
In general, your heart rate slows as you age. Under some abnormal conditions, certain heart tissue is capable of starting a heartbeat, or becoming the "pacemaker," just like the sinus node. An abnormal heartbeat arrhythmia may occur when:.
Symptoms of an arrhythmia can include a feeling that your heart is fluttering heart palpitations , shortness of breath, dizziness, or fainting. Your doctor may do an ECG electrocardiogram to assess the rhythm of the heart.
This painless test involves recording the electrical activity of your heart with several small stickers attached to your chest. Top of the page. Topic Overview What controls the timing of your heartbeat?
Your heart's electrical system controls the timing of your heartbeat by regulating your: Heart rate, which is the number of times your heart beats per minute. Heart rhythm, which is the synchronized pumping action of your four heart chambers. Your heart's electrical system should maintain: A steady heart rate of 60 to beats per minute at rest.
The heart's electrical system also increases this rate to meet your body's needs during physical activity and lowers it during sleep. An orderly contraction of your atria and ventricles this is called a sinus rhythm. How does the heart's electrical system work? Two different types of cells in your heart enable the electrical signal to control your heartbeat: Conducting cells carry your heart's electrical signal.
Muscle cells enable your heart's chambers to contract, an action triggered by your heart's electrical signal. The heartbeat happens as follows: The SA node called the pacemaker of the heart sends out an electrical impulse. The upper heart chambers atria contract. The AV node sends an impulse into the ventricles. The lower heart chambers ventricles contract or pump.
The SA node sends another signal to the atria to contract, which starts the cycle over again. SA node and atria When the SA node sends an electrical impulse, it triggers the following process: The electrical signal travels from your SA node through muscle cells in your right and left atria. The signal triggers the muscle cells that make your atria contract. The atria contract, pumping blood into your left and right ventricles. AV node and ventricles After the electrical signal has caused your atria to contract and pump blood into your ventricles, the electrical signal arrives at a group of cells at the bottom of the right atrium called the atrioventricular node, or AV node.
When the electrical signal leaves the AV node, it triggers the following process: The signal travels down a bundle of conduction cells called the bundle of His, which divides the signal into two branches: one branch goes to the left ventricle, another to the right ventricle. These two main branches divide further into a system of conducting fibres that spreads the signal through your left and right ventricles, causing the ventricles to contract. When the ventricles contract, your right ventricle pumps blood to your lungs and the left ventricle pumps blood to the rest of your body.
How does the heart's electrical system regulate your heart rate? What makes your heart rate speed up or slow down? How does your body control your heart rate? Your body controls your heart by: The sympathetic and parasympathetic nervous systems, which have nerve endings in the heart.
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