Electrophysiology of the Heart

These flashcards cover key terms and concepts related to the electrophysiology of the heart, including the cardiac cycle, the properties of cardiac muscle cells, and the role of pacemaker cells.

Diastole

The phase of the cardiac cycle where the heart muscle relaxes and the chambers fill with blood.

Systole

The phase of the cardiac cycle where the heart muscle contracts, pushing blood out of the ventricles.

Action Potential

An electrical signal that propagates from muscle cell to muscle cell in the heart, initiating contraction.

Pacemaker Cells

Specialized cardiac muscle cells that can spontaneously depolarize and initiate action potentials, responsible for heartbeats.

Sinoatrial (SA) Node

The primary pacemaker of the heart located in the right atrial wall, responsible for initiating each heartbeat.

Atrioventricular (AV) Node

A pathway of cardiac muscle cells that conducts action potentials from the atria to the ventricles, delaying contraction.

Bundle of His

The pathway that provides the only route for action potential propagation between atrial and ventricular cells.

Resting Membrane Potential

The stable, negative charge inside a non-active cardiac muscle cell before it depolarizes.

Norepinephrine

A neurotransmitter that increases heart rate by acting on beta-adrenergic receptors in pacemaker cells.

Acetylcholine

A neurotransmitter that decreases heart rate by acting on muscarinic cholinergic receptors in pacemaker cells.

Funny Na+ Channels

Specialized sodium channels in pacemaker cells that open spontaneously and contribute to pacemaker potentials.

Refractory Period

The time interval during which a second action potential cannot be initiated, allowing for cardiac relaxation and refilling.

Calcium Channels

Channels in cardiac muscle cells that allow influx of Ca²⁺, prolonging the duration of the action potential.

Sympathetic Nervous System

Part of the autonomic nervous system that increases heart rate and the strength of heart contractions.

Parasympathetic Nervous System

Part of the autonomic nervous system that decreases heart rate by influencing pacemaker cells.