Heart Anatomy and Electrical Conduction

Comprehensive vocabulary flashcards covering heart gross anatomy, heart wall layers, valves, systemic and pulmonary pathways, and the cardiac conduction system.

Pericardium (Pericardial sac)

A double-layered serous membrane sac surrounding the heart that provides protection and a smooth, low-friction surface for rhythmic volume changes.

Base (of the heart)

The wide, superior region of the heart, historically named because early anatomists rested hearts on this flat side on examination tables.

Apex (of the heart)

The narrow, inferior tip of the heart pointed downward and tilted slightly toward the left side of the body.

Atria

The two superior chambers of the heart that serve as entryways receiving incoming blood.

Ventricles

The two inferior, muscular chambers of the heart that contract forcefully to pump blood out into the circulatory system.

Sulcus (Sulci)

An external groove, fold, or indentation on the heart surface in which coronary blood vessels travel.

Coronary sulcus (Atrioventricular sulcus)

The circumferential groove encircling the heart like a crown, marking the external boundary between the atria and the ventricles.

Interventricular sulcus

A groove located on the anterior and posterior surfaces of the heart that marks the external boundary between the right and left ventricles.

Auricle

The wrinkled, ear-like flap on the exterior of each atrium that collapses and appears floppy when not filled with blood.

Interventricular septum

The thick internal muscular wall that divides the right ventricle from the left ventricle.

Endocardium

The innermost, thinnest layer of the heart wall, composed of connective tissue fibers and endothelium, that directly contacts circulating blood inside the chambers.

Myocardium

The middle muscular layer of the heart wall composed of cardiac muscle tissue, which is significantly thicker in the ventricles than in the atria.

Epicardium

The outermost layer of the heart wall, which is structurally identical to the visceral layer of the serous pericardium.

Parietal layer of the serous pericardium

The outer layer of the serous pericardium, separated from the visceral layer (epicardium) by a lubricating, fluid-filled cavity.

Cardiac cycle

The sequence of events consisting of one atrial contraction, one ventricular contraction, and a relaxation phase.

Bicuspid valve (Mitral valve / Left atrioventricular valve)

The heart valve composed of two cusps located between the left atrium and the left ventricle.

Tricuspid valve (Right atrioventricular valve)

The heart valve composed of three cusps located between the right atrium and the right ventricle.

Chordae tendineae

Strong, cord-like strands of dense connective tissue connecting the cusps of the atrioventricular valves to papillary muscles in the ventricles.

Papillary muscles

Finger-like muscular projections lining the interior ventricular walls that contract to pull chordae tendineae taut, preventing AV valve inversion during ventricular systole.

Aorta

The largest blood vessel in the body, which arises from the left ventricle and arches around the heart to distribute oxygen-rich blood to systemic organs.

Superior vena cava

A large vein that collects oxygen-poor blood from the head and upper body and empties directly into the right atrium.

Inferior vena cava

A large vein that collects oxygen-poor blood from the trunk and lower body and empties directly into the right atrium.

Pulmonary trunk

The large vessel exiting the right ventricle that carries oxygen-poor blood toward the lungs and branches into the pulmonary arteries.

Pulmonary veins

Four vessels that return newly oxygenated blood from the lungs directly into the left atrium.

Semilunar valves

Pocket-like valves (the aortic valve and pulmonary valve) lacking chordae tendineae that guard the exits from the ventricles into the great arteries.

Systemic circulation

The division of the circulatory system that carries oxygen-rich blood from the left side of the heart to body organs and returns oxygen-poor blood to the right side.

Pulmonary circulation

The division of the circulatory system that carries oxygen-poor blood from the right side of the heart to the lungs and returns oxygen-rich blood to the left side.

Intercalated discs

Specialized cell junctions containing gap junctions that bridge adjacent cardiac muscle cells, allowing rapid ion flow and synchronized contraction.

Autorhythmicity

The unique physiological capacity of cardiac pacemaker cells to initiate rhythmic electrical contractions independently without nervous system input.

Pacemaker cells

Specialized hybrid cardiac cells capable of generating self-regulated action potentials that set the rhythm of the heart.

Sinoatrial node

A cluster of specialized pacemaker cells located in the right atrium that initiates depolarization impulses at approximately $60$ times per minute.

Atrioventricular node

The cluster of conductive cells situated between the atria and ventricles that receives depolarization signals from the sinoatrial node.

Atrioventricular bundle (Bundle of His)

The electrical conduction tract extending from the atrioventricular node down into the interventricular septum.

Purkinje fibers

Terminal conductive fibers that spread throughout the ventricular walls from the apex, causing coordinated ventricular contraction.

P wave

The first deflection on an electrocardiogram (ECG/EKG), representing atrial depolarization that immediately precedes atrial contraction.

QRS complex

The large electrical spike on an ECG representing ventricular depolarization, which triggers ventricular contraction.

T wave

The third wave on an ECG tracing, reflecting ventricular repolarization and tissue resetting for the next cardiac cycle.