Anatomy and Intrinsic Conduction System of the Heart

Vocabulary flashcards covering gross heart anatomy, internal cardiac structures, heart wall layers, intrinsic conduction system components, and circulatory pathways.

Sinoatrial (SA) node

The pacemaker of the heart located in the right atrium just inferior to the entrance to the superior vena cava that generates impulses.

Atrioventricular (AV) node

A node located in the lower atrial septum at the junction of the atria and ventricles where electrical impulses pause for $0.1\,\text{sec}$.

Atrioventricular (AV) bundle (bundle of His)

The conducting tract located in the interventricular septum that receives impulses from the AV node and passes them to the right and left bundle branches.

Subendocardial conducting network (Purkinje fibers)

The terminal portion of the intrinsic conduction system that depolarizes the contractile cells of both ventricles.

Internodal pathway

The pathway through which electrical impulses travel from the SA node to the AV node.

Pulmonary circuit

The system of blood vessels that carries oxygen-poor blood from the right side of the heart to the lungs for gas exchange and returns oxygenated blood to the left side of the heart.

Systemic circuit

The circuit driven by the left side of the heart that pumps oxygenated blood returning from the lungs out to the rest of the body.

Pectinate muscles

Parallel muscular ridges found along the internal walls of the right atrium and auricles.

Trabeculae carneae

Irregular muscular ridges located on the internal walls of the ventricles.

Chordae tendineae

Tiny white fibrous cords that anchor the cusps of the AV valves to the papillary muscles.

Papillary muscle

Cone-like muscular projections from the ventricular wall that attach to chordae tendineae to anchor heart valves.

Ligamentum arteriosum

A fibrous remnant structure connecting the arch of the aorta to the pulmonary trunk.

Fossa ovalis

A shallow oval depression in the interatrial septum, representing the remnant of the fetal foramen ovale.

Tricuspid valve (Right AV valve)

The valve located between the right atrium and the right ventricle that prevents backflow into the right atrium.

Mitral (bicuspid) valve (Left AV valve)

The valve located between the left atrium and the left ventricle.

Semilunar (SL) valves

Valves that open and flatten against vessel walls during ventricular contraction and fill with blood to close when ventricles relax, preventing backflow into the ventricles.

Coronary sinus

A wide venous channel on the posterior heart that collects deoxygenated blood from the cardiac veins and empties into the right atrium.

Brachiocephalic trunk

The first branch of the aortic arch that supplies oxygenated blood to the head, neck, and right arm.

Epicardium

The outermost layer of the heart wall, which is also the visceral layer of the serous pericardium.

Myocardium

The thick middle layer of the heart wall composed of cardiac muscle tissue responsible for pumping action.

Endocardium

The thin endothelial inner lining layer of the heart chambers and valves.