Cardiac Muscle and Conduction System

A set of vocabulary flashcards covering key concepts related to cardiac muscle function and the conduction system of the heart.

Systemic circuit

The part of the cardiovascular system responsible for delivering oxygenated blood from the heart to the tissues of the body.

Cardiac muscle

Striated muscle tissue that forms the walls of the heart, characterized by intercalated discs.

Intercalated discs

Specialized connections between cardiac muscle cells that contain gap junctions for rapid electrical communication.

Gap junctions

Protein channels that allow ions, such as sodium, to pass between adjacent cardiac muscle cells, facilitating rapid conduction of action potentials.

Sodium (Na+)

A positively charged ion (cation) that plays a crucial role in generating action potentials in cardiac muscle cells.

Action potential

A rapid change in membrane potential that occurs when a cardiac muscle cell is excited, leading to contraction.

Sarcoplasm

The cytoplasm of a muscle cell, where calcium is stored and released during muscle contraction.

Sarcoplasmic reticulum

An organelle in muscle cells that stores calcium ions, crucial for muscle contraction.

Pacemaker cells

Specialized cardiac cells that generate and regulate the rhythm of the heartbeat.

SA node

Sinoatrial node, the primary pacemaker of the heart that initiates the cardiac cycle.

AV node

Atrioventricular node, the secondary pacemaker that conducts impulses from the atria to the ventricles.

Ectopic focus

An abnormal pacemaker that takes over when the primary pacemaker (SA node) fails to function.

Arrhythmia

An irregular or abnormal heart rhythm caused by disorganized electrical impulses.

Refractory period

The time following an action potential during which a cardiac muscle cell cannot initiate another action potential.

Depolarization

The process of reducing the membrane potential from its resting state, leading to the generation of an action potential.

Calcium (Ca2+)

A mineral essential for muscle contraction, stored in the sarcoplasmic reticulum.

Desmosomes

Proteins that anchor cardiac muscle cells together, preventing them from separating during contraction.

Intrinsic conduction system

The network of pacemaker cells and conducting fibers responsible for initiating and regulating heartbeats.