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Conduction System of the Heart
The cardiac conduction system produces and transmits electrical impulses that prompt myocardial contraction, ensuring efficient heart function. This intricate system ensures that the heart beats in a coordinated and efficient manner, beginning with the atria and then the ventricles. The conduction system optimizes cardiac output by maintaining this precise sequence, which is crucial for adequate blood circulation.
This system relies on the unique properties of nodal and Purkinje cells:...
This system relies on the unique properties of nodal and Purkinje cells:...
Conduction System of the Heart
Autorhythmicity is a term that refers to the heart's inherent ability to generate electrical signals and instigate muscle contractions. This self-regulating conduction system within the heart consists of two key components: the pacemaker cells and specialized conducting cells.
The pacemaker cells are located in two primary nodes: the sinoatrial (SA) node and the atrioventricular (AV) node. The SA node pacemaker cells can autonomously depolarize, triggering an action potential that leads to the...
The pacemaker cells are located in two primary nodes: the sinoatrial (SA) node and the atrioventricular (AV) node. The SA node pacemaker cells can autonomously depolarize, triggering an action potential that leads to the...
Electrophysiology of Normal Cardiac Rhythm
The normal cardiac rhythm is a synchronized electrical activity that facilitates the regular and coordinated contraction of the heart muscle. This process is essential for efficient blood circulation throughout the body. The fundamental elements involved in establishing and maintaining this rhythm include the unique electrical properties of cardiac muscle cells, the sinoatrial (SA) node's pacemaker function, the specialized conducting system, and the ionic mechanisms underlying each phase of...
Mechanism of Cardiac Arrhythmias
Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.
Cardiac Action Potential
Cardiac action potentials are essential for proper heart function, enabling the rhythmic contractions needed for adequate blood circulation. Nodal cells and Purkinje fibers, specialized for electrical conduction, generate these action potentials.
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
The Cardiac Cycle
The heart beats rhythmically in a sequence called the cardiac cycle—a rapid coordination of contraction (systole) and relaxation (diastole).
The Process
Electrical signals—sent from the sinoatrial (SA) node in the right atrial wall to the atrioventricular (AV) node between the right atrium and right ventricle—cause both atria to simultaneously contract. When the signal reaches the AV node, it pauses for approximately a tenth of a second, allowing the atria to contract and empty blood into the...
The Process
Electrical signals—sent from the sinoatrial (SA) node in the right atrial wall to the atrioventricular (AV) node between the right atrium and right ventricle—cause both atria to simultaneously contract. When the signal reaches the AV node, it pauses for approximately a tenth of a second, allowing the atria to contract and empty blood into the...
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Related Experiment Video
Updated: Jun 4, 2026

09:20
Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice
Published on: July 5, 2021
[Computer simulations of pacemaker shift in the sinoatrial node].
Biofizika
|January 28, 2011
Summary
Simulations show that acetylcholine application in the sinoatrial node can disrupt normal electrical pulse propagation, causing conduction blocks and shifting the leading pacemaker center. This reveals acetylcholine
Area of Science:
- Computational biology
- Cardiac electrophysiology
- Pharmacology
Context:
- The sinoatrial node generates electrical impulses regulating heart rate.
- Understanding its electrical dynamics is crucial for cardiac health.
- Acetylcholine is a key neurotransmitter affecting heart function.
Purpose:
- To simulate and analyze electrical pulse initiation and propagation in the sinoatrial node.
- To investigate the effects of acetylcholine on sinoatrial node electrical activity.
- To model the formation and migration of leading centers under different conditions.
Summary:
- Simulations revealed that under normal conditions, the sinoatrial node forms one or a few leading centers for electrical pulse initiation.
- Application of acetylcholine was found to induce temporary functional conduction blocks.
- Acetylcholine application caused the leading center to migrate within the sinoatrial node tissue.
Impact:
- Provides insights into the mechanisms of cardiac rhythm regulation.
- Helps understand the electrophysiological effects of acetylcholine in the heart.
- Informs potential therapeutic strategies for cardiac arrhythmias.

