Automaticity

Definition

Automaticity is the ability of cardiac cells to generate spontaneous electrical impulses without external stimulation. This property is primarily found in pacemaker cells within the heart.

5 Must Know Facts For Your Next Test

1. Automaticity is essential for initiating and regulating the heartbeat.
2. The sinoatrial (SA) node, located in the right atrium, has the highest rate of automaticity and serves as the natural pacemaker of the heart.
3. Automaticity can be influenced by autonomic nervous system inputs, with sympathetic activation increasing and parasympathetic activation decreasing the rate of impulse generation.
4. Abnormalities in automaticity can lead to arrhythmias, such as tachycardia or bradycardia.
5. Medications like beta-blockers can affect automaticity by altering ion channel activity within pacemaker cells.

Review Questions

• What role does automaticity play in the functioning of cardiac cells?
• Which part of the heart exhibits the highest level of automaticity?
• How can autonomic nervous system inputs influence cardiac automaticity?

Related terms

Sinoatrial Node:

A group of cells located in the right atrium that act as the primary pacemaker of the heart due to their high rate of automaticity.

Arrhythmia:

An irregular heartbeat resulting from abnormalities in how electrical impulses are generated or conducted within the heart.

Beta-Blockers:

A class of medications that reduce heart rate and contractility by blocking beta-adrenergic receptors, thereby affecting cardiac automaticity.