Chapter 18: The Cardiovascular System: The Heart

Comprehensive vocabulary flashcards generated from the Chapter 18 transcript covering structural features, blood flow pathways, valves, coronary circulation, and microscopic cardiac anatomy.

Pulmonary Circuit

The pathway where the right side of the heart receives oxygen-poor blood from tissues and pumps it to the lungs to remove $CO_2$ and pick up $O_2$.

Systemic Circuit

The long, high-friction pathway where the left side of the heart receives oxygenated blood from the lungs and pumps it to body tissues.

Right Atrium

The receiving chamber of the heart that receives blood returning from the systemic circuit via the superior vena cava, inferior vena cava, and coronary sinus.

Left Atrium

The receiving chamber of the heart that receives oxygenated blood returning from the pulmonary circuit via four pulmonary veins.

Right Ventricle

The pumping chamber that makes up most of the anterior surface of the heart and pumps blood into the pulmonary trunk.

Left Ventricle

The pumping chamber forming the posteroinferior surface that pumps blood into the aorta; its walls are $3\times$ thicker than the right ventricle.

Mediastinum

The anatomical space between the second rib and fifth intercostal space, superior to the diaphragm, where the heart is located.

Apex

The inferior tip of the heart pointing toward the left hip; the apical impulse is palpated between the fifth and sixth ribs, just below the left nipple.

Fibrous Pericardium

The superficial layer of the double-walled pericardial sac that protects the heart, anchors it to surrounding structures, and prevents overfilling.

Serous Pericardium

The deep, two-layered membrane composed of an outer parietal layer and an inner visceral layer (epicardium) separated by the fluid-filled pericardial cavity.

Pericarditis

Inflammation of the pericardium that causes roughened membrane surfaces, producing a creaking pericardial friction rub sound heard with a stethoscope.

Cardiac Tamponade

A condition in which excess fluid compresses the heart within the pericardial sac, limiting its pumping ability.

Epicardium

The outermost layer of the heart wall, which serves as the visceral layer of the serous pericardium.

Myocardium

The middle layer of the heart wall consisting of spiral bundles of contractile cardiac muscle cells and a connective tissue cardiac skeleton.

Endocardium

The innermost layer of the heart wall continuous with the endothelial lining of blood vessels, which lines the chambers and covers valve structures.

Fossa Ovalis

A shallow depression located in the interatrial septum that is a remnant of the fetal heart's foramen ovale.

Coronary Sulcus

Also known as the atrioventricular groove; an anatomical groove that encircles the junction between the atria and the ventricles.

Auricles

Small, wrinkled appendages located on the atria that function to increase atrial volume.

Pectinate Muscles

Muscle ridges present in both atria, located in both posterior and anterior regions separated by the crista terminalis in the right atrium, and only in the auricles of the left atrium.

Trabeculae Carneae

Irregular ridges of muscle found along the internal walls of the discharging ventricles.

Papillary Muscles

Internal ventricular muscle structures that project into the lumen to anchor the chordae tendineae.

Tricuspid Valve

The right atrioventricular (AV) valve that prevents the backflow of blood into the right atrium during ventricular contraction.

Mitral Valve

The left atrioventricular (AV) valve, also called the bicuspid valve, that prevents the backflow of blood into the left atrium during ventricular contraction.

Chordae Tendineae

Fibrous cords that anchor the cusps of the atrioventricular valves to the papillary muscles, holding the valve flaps closed during contraction.

Semilunar (SL) Valves

Valves (aortic and pulmonary) that open and close in response to pressure changes to prevent backflow into the ventricles when they relax.

Incompetent Valve

A homeostatic valve condition where blood leaks backward, forcing the heart to repeatedly repump the same volume of blood.

Valvular Stenosis

A condition characterized by stiffened valve flaps that constrict the opening, forcing the heart to exert greater force to propel blood.

Left Coronary Artery

Artery arising from the base of the aorta that branches into the anterior interventricular artery and circumflex artery to supply the interventricular septum, anterior walls, left atrium, and posterior left ventricle.

Right Coronary Artery

Artery arising from the base of the aorta that branches into the right marginal artery and posterior interventricular artery to supply the right atrium and most of the right ventricle.

Coronary Sinus

A large venous vessel on the posterior surface formed by the merging great, middle, and small cardiac veins that empties blood directly into the right atrium.

Angina Pectoris

Chest pain caused by a temporary, fleeting deficiency in blood delivery to the myocardium, resulting in weakened cardiac cells.

Myocardial Infarction

Commonly known as a heart attack; prolonged coronary blockage leading to cardiac cell death where damaged areas are replaced with noncontractile scar tissue.

Intercalated Discs

Specialized plasma membrane junctions between cardiac muscle cells containing desmosomes to resist pulling forces and gap junctions for electrical coupling.

Functional Syncytium

The operational behavior of the myocardium as a single coordinated contraction unit due to electrical connection through gap junctions.