regulation of cardiac conduction

Definition

Target type: biologicalprocess

Any process that modulates the frequency, rate or extent of cardiac conduction. [GO_REF:0000058, GOC:BHF, GOC:mtg_cardiac_conduct_nov11, GOC:rph, GOC:TermGenie, PMID:12967627]

The regulation of cardiac conduction is a complex process that ensures the heart beats rhythmically and efficiently. It involves a precise interplay of electrical and chemical events within the heart's specialized conducting system, ultimately governing the speed and timing of electrical impulses that trigger muscle contractions.

Here's a detailed breakdown:

**1. Initiation of the Electrical Signal:**

* The heartbeat originates in the sinoatrial (SA) node, located in the right atrium. This specialized pacemaker tissue spontaneously generates electrical impulses due to the influx of sodium ions into its cells.
* This electrical signal, also known as the action potential, spreads through the atria causing them to contract.

**2. Conduction through the Atria:**

* The electrical impulse travels through the atrial muscle, reaching the atrioventricular (AV) node. This node serves as a gatekeeper, slowing the signal down briefly to ensure the ventricles are fully filled with blood before they contract.

**3. Conduction through the Ventricles:**

* From the AV node, the impulse passes through the bundle of His, a specialized bundle of fibers that conduct the signal rapidly to the ventricular walls.
* The bundle of His divides into two branches, right and left, extending down to the apex of the heart.
* These branches further divide into smaller fibers called Purkinje fibers, which spread the electrical impulse throughout the ventricular muscle, causing them to contract.

**4. Regulation and Control:**

* **Autonomic Nervous System:** The sympathetic nervous system (SNS) increases heart rate and conduction velocity by releasing norepinephrine, which binds to beta-adrenergic receptors on heart cells, leading to increased calcium influx and faster depolarization. The parasympathetic nervous system (PNS), via acetylcholine, decreases heart rate and conduction velocity by slowing down depolarization.
* **Hormones:** Epinephrine and norepinephrine (from the adrenal glands) have similar effects as the SNS. Thyroid hormones (T3 and T4) also increase heart rate and conduction velocity.
* **Electrolytes:** The concentration of ions like potassium, calcium, and sodium significantly influences the conduction process. For example, low potassium levels (hypokalemia) can disrupt conduction and increase the risk of arrhythmias.
* **Drugs:** Medications like beta-blockers slow down heart rate by blocking the effects of the SNS, while calcium channel blockers decrease conduction velocity by reducing calcium influx.

**5. Importance of Efficient Conduction:**

* Precise regulation of cardiac conduction is essential for a coordinated heart beat. Disruptions in this process, such as irregular electrical activity or blockages in the conduction pathway, can lead to various heart rhythm disorders (arrhythmias), including bradycardia (slow heart rate), tachycardia (fast heart rate), and fibrillation (chaotic electrical activity).

**In summary, the regulation of cardiac conduction is a finely tuned process involving a complex interplay of electrical, chemical, and physiological factors that ensure efficient and coordinated heart function. Any disruption in this delicate balance can significantly impact heart health.'**
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Proteins (12)

Compounds (356)