The key difference between the AV bundle (Bundle of His) and Purkinje fibers lies in their location and function within the heart's electrical conduction system: the AV bundle carries the electrical signal from the AV node down the interventricular septum, while the Purkinje fibers distribute that signal throughout the ventricles, triggering their contraction.
Here's a more detailed breakdown:
AV Bundle (Bundle of His)
- Location: Extends from the AV node down the interventricular septum (the wall separating the left and right ventricles).
- Function: Serves as the crucial pathway for the electrical impulse to travel from the atria (upper chambers) to the ventricles (lower chambers). It's essentially the "highway" connecting the AV node to the ventricular conduction system. It branches into the left and right bundle branches.
- Importance: A properly functioning AV bundle ensures coordinated contraction between the atria and ventricles. A block in the AV bundle (bundle branch block) can lead to irregular heart rhythms.
Purkinje Fibers
- Location: A network of specialized cells distributed throughout the ventricular myocardium (heart muscle). They are located after the bundle branches.
- Function: Rapidly conduct the electrical impulse received from the bundle branches to the ventricular muscle cells, causing a synchronized and powerful contraction of the ventricles. This efficient and widespread distribution is crucial for proper ejection of blood.
- Importance: They are the final component of the heart's conduction system. Damage to Purkinje fibers can lead to arrhythmias and inefficient ventricular contraction.
Table Summarizing the Differences
| Feature | AV Bundle (Bundle of His) | Purkinje Fibers |
|---|---|---|
| Location | Interventricular septum (from AV node) | Ventricular myocardium |
| Function | Transmits impulse from AV node to ventricles | Distributes impulse throughout ventricles |
| Position | Before Purkinje fibers | After the bundle branches |
| Signal Delivery | Conducts signal to bundle branches | Conducts signal directly to ventricular muscle cells |
In simpler terms:
Imagine the heart's electrical system as a road network. The AV node is the starting point. The AV bundle is the main highway leading from the city center (AV node) to the suburbs (ventricles). The Purkinje fibers are the many local streets that branch out throughout the suburbs, ensuring every house (ventricular muscle cell) receives the signal to turn on (contract).
