The key difference between Bundle of His and Purkinje Fibres is that Bundle of His is a collection of specialized heart muscle cells for electrical conduction while Purkinje fibres are thin filaments originating from the left posterior fascicle and left anterior fascicles that help in distributing impulses to the ventricular muscles.
There is an electrical conduction system in our heart, which is known as the cardiac conduction system. It generates and propagates electrical impulses in order to contract and relax the heart in a rhythmic way. It comprises of SA node, AV node, Bundle of His, left bundle branch, right bundle branch, anterior and posterior fascicles, Purkinje fibres, etc.
Bundle of His receives impulses from the AV node. It is a collection of thin, specialized muscle cells. Bundle of His further divides into left and right bundle branches. Left bundle branch again divides into left anterior and left posterior fascicles. These left anterior and left posterior fascicles give rise to Purkinje fibres, which are thin filaments that distribute impulses to the ventricular muscles.
CONTENTS
1. Overview and Key Difference
2. What is Bundle of His
3. What is Purkinje Fibres
4. Similarities Between Bundle of His and Purkinje Fibres
5. Side by Side Comparison – Bundle of His vs Purkinje Fibres in Tabular Form
6. Summary
What is Bundle of His?
Bundle of His or His bundle is a collection of heart muscle cells specialized for electrical conduction. It is an integral part of the heart electrical conduction system. It transmits electrical pulses from the atrioventricular node (AV node) to the ventricles of the heart.
Figure 01: Bundle of His
Bundle of His branches into two parts as left and right bundle branches. Left bundle branch again divides into left anterior and left posterior fascicles. Then these fascicles and bundles give rise to thin filaments called Purkinje fibers that distribute the impulse to the ventricular muscle.
What are Purkinje Fibres?
Purkinje fibres are a network of thin filaments of muscle cells split in ventricle walls. It is a part of the ventricular conduction system of the heart. Left anterior and left posterior fascicles give rise to Purkinje fibres. The main function of the Purkinje fibres is to distribute the electrical impulses to ventricular myocardium and activate left and right ventricles.
Figure 02: Purkinje Fibres
Purkinje fibres are specialized for rapid impulse conduction. In order to do that, they have many gap junctions as well as wide diameters. Moreover, they have fewer myofibrils and no T-tubules. However, they consist of lots of glycogen and mitochondria. Most importantly, Purkinje fibres are larger than cardiac muscle cells.
What are the Similarities Between Bundle of His and Purkinje Fibres?
- Bundle of His and Purkinje fibres are parts of the cardiac conduction system found in the heart.
- They initiate and coordinate electrical pulse needed for the rhythmic and synchronized contractions of the atria and ventricles.
- Both receive conductive signals originating from the AV node.
What is the Difference Between Bundle of His and Purkinje Fibres?
Bundle of His is a collection of specialized heart muscle cells that transmit electrical impulses from the AV node in the heart to the muscle cells of the heart wall. Meanwhile, Purkinje fibres are thin filaments that distribute electrical impulses to the ventricle myocardium and activate right and left ventricles. So, this is the difference between Bundle of His and Purkinje fibres.
Moreover, AV node continuous with Bundle of His, while left anterior and posterior fascicles continuous with Purkinje fibres. Therefore, this is also a significant difference between Bundle of His and Purkinje fibres.
Summary – Bundle of His vs Purkinje Fibres
Bundle of His and Purkinje fibres are specific heart muscle tissues responsible for the generation of the heart impulses. In fact, they are specialized in conducting fibres found in the cardiac conduction system. Bundle of His passes electrical impulses from the AV node to the right and left bundle branches. Left bundle branch transmits impulses to Purkinje fibres, which are thin filaments split in the ventricle walls and distribute impulses to the ventricular myocardium. So, this is the summary of the difference between bundle of His and Purkinje fibres.
Reference:
1. “Clinical Electrocardiography and ECG Interpretation.” ECG Learning, Available here.
2. “Altered Impulse Conduction.” Image for Cardiovascular Physiology Concepts, Richard E Klabunde PhD, Available here.
Image Courtesy:
1. “ConductionsystemoftheheartwithouttheHeart-en” By Madhero88 (original files); Angelito7 (this SVG version); – ConductionsystemoftheheartwithouttheHeart.png & ConductionsystemoftheheartwithoutHeart.svg (CC BY-SA 3.0) via Commons Wikimedia
2. “ECG Principle fast” By Kalumet – selbst erstellt = Own work (CC BY-SA 3.0) via Commons Wikimedia
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