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Anatomy and Functions of Heart’s Electrical System

Last Updated : 13 Jan, 2024
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Understanding the heart’s electrical system is aided by understanding its structure. The human heart is divided into four chambers. The upper chambers are known as the left and right atrium (both are referred to as atria). The left and right ventricles are the lower chambers. Blood flows through your heart in the following sequence (the steps on the left and right occur simultaneously)



As electricity flows through the heart, it causes each part to contract. This is known as an electrical cascade. While all the cardiac muscles in the heart can conduct electricity, the cascade travels at different speeds in certain areas of the heart — the electrical conduction system.

The cascade proceeds in the following order through the electrical conduction system:

The Sinoatrial Node The sinoatrial (SA) node is a group of cells that acts as the heart’s natural pacemaker. The SA node is located in a wall of the heart’s right atrium. The upper chambers of the heart begin to squeeze at this point.
Atrioventricular node (AVN) The atrioventricular (AV) node is located in the wall between your heart’s upper chambers. This node is similar to the SA node, but it is smaller, and electricity moves more slowly here. The slowing effect allows the ventricles to expand and fill with blood.
Bundle of His The Bundle of His (pronounced “hiss”) is a cell cluster that extends from the AV node and travels down the centre of your heart. Because they conduct electricity faster than surrounding tissue, they act similarly to a lightning rod, directing the electrical cascade deeper into the heart.
Branch bundles The Bundle of His splits into two branches at the bundle branches. The split occurs at roughly the same level as the top and bottom chambers of the heart. The branches carry the electrical cascade to the heart’s outer regions, particularly the ventricles.
Purkinje cells The Purkinje fibres form a web-like network of conducting segments as the bundle branches fan out. The His-Purkinje system, which resembles an upside-down umbrella, is often described as the Bundle of His, bundle branches, and Purkinje fibres. The handle is the Bundle of His, the stem is the bundle branches, and the canopy is the Purkinje fibres.

Electricity travels down and then spreads out at the heart’s bottom. The electricity then travels upward and along the heart’s outer areas. This is how the heart moves blood up and out of the body.

Common Disorders

The heart conducts electricity in a specific way, as described above, and its function is best when this sequence is maintained. Any disruption in this sequence can result in abnormal heart rhythms and patterns known as arrhythmias.

Arrhythmias primarily occur in two ways:

  • Bradycardia: A slow heart rate caused by problems with the SA node, the AV node, or the His-Purkinje system. These are typically caused by damage or scarring of the heart’s electrical pathways, which slows or stops electrical current in certain locations.
  • Tachycardia: This term refers to rapid or rapid heartbeats, which are frequently caused by a phenomenon known as re-entry. When this happens, a persistent electrical loop forms, causing certain parts of the heart to beat too quickly or incorrectly. Tachycardia can begin in the bottom chambers of the heart (ventricular tachycardia) or above the AV node (supraventricular tachycardia).


Electrical impulses are used by the body to control when muscles flex and relax, and your heart is no exception. However, the heart must do this constantly, whether sleeping or awake. It does this by relying on a part of the nervous system known as the autonomic nervous system. This is the unconscious part of your nervous system that controls the functions of your body that you are not aware of. This includes your heart, breathing, digestion, and other bodily functions.

The timing of the heart’s action is also important. It uses the heart’s conduction system to send electrical impulses rather than to the brain. To accomplish this, the brain sends signals to your heart’s electrical system via your autonomic nervous system. When that system is activated, an electrical pulse is sent through the heart muscle. This causes your heart’s chambers to squeeze in a specific order, resulting in a heartbeat.

When an organism is at rest, this happens 50 to 100 times per minute under normal conditions. When you’re active, your heart beats faster and faster.

Functions of the Heart Muscle 


Smooth muscle cells

Cardiac muscle cells

Skeletal muscle cells

How it is managed Unconscious(without you thinking about it)  Unconscious Conscious(these moves when you think about it). 
Wheel-shaped. When relaxed, the shape is more round; when flexed, the shape is more oval. Rectangular. It creates a mesh-like pattern with cells surrounding it.  Long, fibre-like form.
Appearance Different cells, each with its own nucleus. Different cells, each with its own nucleus. Across their entire width. Larger fibres of cells with numerous nuclei form, across their entire width.
Contraction speed  Slow Fast Variable.
Action timing The pattern is repeated. The pattern is repeated. Upon instruction.

FAQs on Heart’s Electrical System

Question 1: What are the three main components of the heart’s electrical system?


These muscle cells communicate with the rest of the heart muscle, causing it to contract. This group of muscle cells is referred to as the cardiac conduction system. The system’s main components are the SA node, AV node, HIS bundle, bundle branches, and Purkinje fibers.

Question 2: What is the order of the heart’s electrical pathway?


The cardiac conduction system is made up of the following structures in the following order: the SA node, the internodal pathway and Bachmann’s bundle, the AV node, the bundle, the bundle branches, and the Purkinje fibres

Question 3: What causes electrical problems in the heart?


Electrolytes, which are substances in the blood that help trigger and send electrical impulses to the heart, include potassium, sodium, calcium, and magnesium. An electrolyte imbalance, for example, if they are too low or too high, can interfere with heart signalling and cause irregular heartbeats.

Question 4: Why is the SA node called the pacemaker?


In a healthy heart, the sinus node continuously generates electrical impulses, establishing the normal rhythm and rate. As a result, the SA node is known as the natural pacemaker of the heart.

Question 5: Is it possible that electrical heart issues are inherited?


When electrical signals pass through this node, the heart can beat extremely fast. This causes an arrhythmia known as paroxysmal supraventricular tachycardia. This syndrome has been passed down through families in some cases. However, the majority of people who develop this condition have no family history.

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