still heart

Right-side cardiovascular circuit pumping oxygen-poor blood to the lungs

Pulmonary circuit

Left-side cardiovascular circuit pumping oxygenated blood throughout the body

Systemic circuit

Superior receiving chambers of the heart

Atria

Inferior muscular pumping chambers of the heart

Ventricles

Central compartment of the thoracic cavity between the lungs housing the heart

Mediastinum

Pointed inferior-lateral tip of the heart pointing left of midline

Apex

Broad, flat posterior surface of the heart

Base

Double-walled fibroserous sac enclosing and protecting the heart

Pericardium

Tough external layer of dense connective tissue holding the heart in place

Fibrous pericardium

Deep, thin two-layered lubricating serous membrane lining the heart

Serous pericardium

Outer layer of serous pericardium adhering to fibrous pericardium

Parietal layer

Inner layer of serous pericardium adhering directly to heart surface

Visceral layer

Slit-like lubricating fluid space between parietal and visceral pericardial layers

Pericardial cavity

Visceral layer of serous pericardium forming the heart wall's outer surface

Epicardium

Middle layer of heart wall consisting of contractile cardiac muscle bundles

Myocardium

Endothelial sheet lining interior chambers and covering valve surfaces

Endocardium

Internal muscular partition separating right and left ventricles

Interventricular septum

Internal membranous partition separating right and left atria

Interatrial septum

External groove encircling heart between atria and ventricles

Coronary sulcus

Anterior groove marking division between right and left ventricles

Anterior interventricular sulcus

Posterior groove marking division between right and left ventricles

Posterior interventricular sulcus

Vein delivering deoxygenated systemic blood from upper body to right atrium

Superior vena cava

Vein delivering deoxygenated systemic blood from lower body to right atrium

Inferior vena cava

Large venous channel returning cardiac venous blood into right atrium

Coronary sinus

Wrinkled, flap-like outer pouch extending from an atrium

Auricle

Parallel, comb-like muscular ridges along anterior wall of right atrium

Pectinate muscles

Internal C-shaped muscular ridge landmark separating smooth and pectinate atrial regions

Crista terminalis

Shallow oval depression on interatrial septum marking fetal shunt closure

Fossa ovalis

Embryonic interatrial opening that closes to form the fossa ovalis

Foramen ovale

Three-cusp valve located between right atrium and right ventricle

Tricuspid valve

Vessel carrying deoxygenated blood exiting right ventricle toward lungs

Pulmonary trunk

Irregular muscular ridges along internal surfaces of ventricular walls

Trabeculae carneae

Cone-shaped muscular projections anchoring chordae tendineae in ventricles

Papillary muscles

Fibrous tendon cords tethering AV valve cusps to papillary muscles

Chordae tendineae

Crescent-pocketed valve guarding exit from right ventricle to pulmonary trunk

Pulmonary semilunar valve

Four vessels delivering oxygen-rich blood from lungs into left atrium

Pulmonary veins

Two-cusped atrioventricular valve between left atrium and left ventricle

Mitral valve

Large systemic artery receiving oxygenated blood from left ventricle

Aorta

Semilunar valve guarding exit from left ventricle into aorta

Aortic semilunar valve

First major branch branching off aortic arch

Brachiocephalic trunk

Middle branch arising off aortic arch

Left common carotid artery

Third branch arising off aortic arch

Left subclavian artery

Fibrous band remnant connecting aortic arch and pulmonary trunk

Ligamentum arteriosum

Dense connective tissue framework encircling and anchoring all four heart valves

Cardiac skeleton

First heart sound caused by closure of AV valves

Lub

Second heart sound caused by closure of semilunar valves

Dup

Cardiac cycle phase during which chambers contract

Systole

Cardiac cycle phase during which chambers relax and fill

Diastole

Delicate loose connective tissue surrounding and binding individual cardiac muscle fibers

Endomysium

Specialized end-to-end cellular junctions connecting adjacent cardiac muscle cells

Intercalated discs

Desmosome-like junctions anchoring sarcolemmas together across intercalated discs

Fasciae adherens

Pore junctions allowing ion exchange and electrical synchronization across cardiac cells

Gap junctions

Internal sarcoplasmic organelle storing and releasing calcium ions

Sarcoplasmic reticulum

Intrinsic capability of cardiac tissue to contract rhythmically without nerve signals

Inherent rhythmicity

Crescent-shaped atrial pacemaker setting inherent heartbeat contraction rate

Sinoatrial node

Atrial pathway transmitting impulses from SA node to AV node

Internodal pathway

Specialized tissue mass delaying electrical impulse by 0.1 second before ventricles

Atrioventricular node

Sole electrical conduction pathway passing impulses from atria into ventricles

Atrioventricular bundle

Conduction pathways coursing down either side of interventricular septum

Bundle branches

Subendocardial conduction fibers directly stimulating ventricular contractile cells

Purkinje fibers

Autonomic nerve network near base of heart modulating heart function

Cardiac plexus

Cranial nerve carrying parasympathetic fibers to slow heart rate

Vagus nerve

Extrinsic nerves from chain ganglia increasing heart rate and contractile force

Sympathetic cardiac nerves

Medullary center sending parasympathetic inhibitory signals to heart

Cardioinhibitory center

Medullary center sending sympathetic acceleratory signals to heart

Cardioacceleratory center

Left aortic base branch distributing blood to left ventricle and atrium

Left coronary artery

LCA branch running in anterior groove down to apex, clinically called LAD

Anterior interventricular artery

LCA branch coursing along posterior coronary sulcus

Circumflex artery

Right aortic base branch coursing along right coronary sulcus

Right coronary artery

RCA branch extending along inferior lateral right ventricle border

Right marginal artery

RCA branch coursing in posterior groove toward apex, clinically called PDA

Posterior interventricular artery

Anterior venous vessel running in anterior interventricular sulcus into coronary sinus

Great cardiac vein

Posterior venous vessel running alongside posterior interventricular artery into coronary sinus

Middle cardiac vein

Venous vessel running alongside right marginal artery into coronary sinus

Small cardiac vein

Tiny anterior veins draining directly into anterior wall of right atrium

Anterior cardiac veins