Cardiovascular System – The Heart (Lecture Unit #2, BIOL 2222, Ch. 19)

Vocabulary flashcards covering anatomy, physiology, conduction, and clinical aspects of the heart based on Chapter 19 lecture notes.

Cardiovascular System

The heart plus blood vessels; transports blood to deliver O₂/nutrients and remove CO₂/wastes.

Perfusion

Blood flow delivered per minute per gram of tissue (mL / min / g).

Heart

Four-chambered double pump that drives pulmonary and systemic circulation.

Pulmonary Circuit

Right-side circulation that carries deoxygenated blood to the lungs and returns oxygenated blood to the heart.

Systemic Circuit

Left-side circulation that delivers oxygenated blood to body tissues and returns deoxygenated blood to the heart.

Artery

Vessel that carries blood away from the heart (usually oxygenated).

Vein

Vessel that returns blood to the heart (usually deoxygenated).

Capillary

Microscopic vessel where gas, nutrient, and waste exchange occurs.

Right Atrium

Receiving chamber for deoxygenated blood from the systemic veins (SVC, IVC, coronary sinus).

Right Ventricle

Pumps deoxygenated blood into the pulmonary trunk toward the lungs.

Left Atrium

Receives oxygenated blood from the four pulmonary veins.

Left Ventricle

Pumps oxygenated blood into the aorta for systemic distribution; thickest cardiac wall.

Superior Vena Cava

Great vein that returns blood from structures above the diaphragm to the right atrium.

Inferior Vena Cava

Great vein that returns blood from structures below the diaphragm to the right atrium.

Pulmonary Trunk

Large artery leaving the right ventricle; splits into right and left pulmonary arteries.

Pulmonary Arteries

Vessels that transport deoxygenated blood from the pulmonary trunk to the lungs.

Pulmonary Veins

Four veins that return oxygenated blood from the lungs to the left atrium.

Aorta

Largest artery; carries oxygenated blood from the left ventricle to systemic circulation.

Atrioventricular (AV) Valves

Valves located between atria and ventricles that prevent backflow into atria.

Right AV (Tricuspid) Valve

Three-cusped valve between right atrium and right ventricle.

Left AV (Mitral/Bicuspid) Valve

Two-cusped valve between left atrium and left ventricle.

Semilunar Valves

Valves at the exits of ventricles that prevent backflow from great arteries.

Pulmonary Semilunar Valve

Valve between right ventricle and pulmonary trunk.

Aortic Semilunar Valve

Valve between left ventricle and aorta.

Chordae Tendineae

Tendinous cords that anchor AV valve cusps to papillary muscles.

Papillary Muscles

Ventricular muscles that tighten chordae tendineae during contraction.

Incompetent Valve

Damaged valve that allows blood to regurgitate, forcing the heart to repump blood.

Valvular Stenosis

Stiffened valve flaps that narrow the opening, increasing the heart’s workload.

Pericardium

Double-walled sac surrounding the heart for protection and anchoring.

Fibrous Pericardium

Tough outer layer of pericardium; prevents overfilling and anchors heart.

Parietal Layer (Serous Pericardium)

Serous membrane lining the internal surface of the fibrous pericardium.

Visceral Layer (Epicardium)

Serous membrane adhered to the heart surface; outer layer of heart wall.

Pericardial Cavity

Space between serous layers; contains lubricating serous fluid.

Pericarditis

Inflammation of the pericardium, often causing friction rub and possibly cardiac tamponade.

Epicardium

Outer layer of the heart wall; same as visceral pericardium.

Myocardium

Middle, muscular layer of heart wall composed of cardiac muscle tissue.

Endocardium

Smooth inner lining of heart chambers and valves; continuous with blood vessel endothelium.

Fibrous Skeleton

Dense connective tissue framework that supports valves, anchors muscle, and electrically insulates atria from ventricles.

Spiral Arrangement

Helical orientation of cardiac muscle fibers enabling wringing action during contraction.

Pectinate Muscles

Ridges of muscle on anterior atrial walls and auricles.

Fossa Ovalis

Oval depression in interatrial septum; remnant of fetal foramen ovale.

Trabeculae Carneae

Irregular muscular ridges on ventricular walls.

Coronary Circulation

Functional blood supply that nourishes the heart wall.

Right Coronary Artery

Artery in coronary sulcus that branches into right marginal and posterior interventricular arteries.

Posterior Interventricular Artery

Supplies posterior walls of both ventricles; branch of right coronary artery.

Right Marginal Artery

Supplies the right heart border; branch of right coronary artery.

Left Coronary Artery

Artery branching into circumflex and anterior interventricular arteries.

Circumflex Artery

Supplies left atrium and posterior left ventricle.

Anterior Interventricular Artery (LAD)

Supplies anterior walls of both ventricles; nicknamed “widow-maker.”

Great Cardiac Vein

Runs with LAD; drains into coronary sinus.

Middle Cardiac Vein

Runs with posterior interventricular artery; drains into coronary sinus.

Small Cardiac Vein

Runs with right marginal artery; drains into coronary sinus.

Coronary Sinus

Large venous channel that collects coronary blood and empties into right atrium.

Functional End Arteries

Coronary arteries whose blockage leads to myocardial tissue death due to minimal anastomoses.

Congestive Heart Failure

Inability of heart to pump adequately, leading to systemic or pulmonary edema.

Cardiomegaly

Enlargement of the heart, often from hypertension or heart disease.

Hypertrophic Cardiomyopathy

Pathologic thickening of heart wall that restricts chamber volume and output.

Sinoatrial (SA) Node

Pacemaker located in right atrium; initiates heartbeat.

Atrioventricular (AV) Node

Electrical gateway to ventricles; delays impulse ~0.1 s.

AV Bundle (Bundle of His)

Only electrical connection between atria and ventricles; splits into branches.

Purkinje Fibers

Large diameter fibers that rapidly spread impulse through ventricular myocardium.

Pacemaker Potential

Gradual depolarization in SA nodal cells due to slow Na⁺ influx leading to spontaneous threshold.

Functional Syncytium

Mass of cells that function as a unit because of gap junction coupling.

Intercalated Discs

Specialized junctions connecting cardiac cells, containing desmosomes and gap junctions.

Desmosome

Mechanical junction in intercalated discs that prevents cell separation during contraction.

Gap Junction

Channel within intercalated discs allowing ion flow for electrical coupling.

Frank–Starling Law

The greater the ventricular filling (preload), the stronger the contraction and higher the stroke volume.

Preload

Degree of cardiac muscle stretch before contraction; related to venous return and EDV.

Afterload

Resistance the ventricles must overcome to eject blood; mainly arterial pressure.

Contractility

Force of contraction at a given muscle length; influenced by inotropic agents.

Stroke Volume (SV)

Volume of blood ejected by one ventricle each beat; SV = EDV – ESV.

Heart Rate (HR)

Number of heartbeats per minute.

Cardiac Output (CO)

Blood volume pumped by each ventricle per minute; CO = HR × SV.

Positive Chronotropic Agent

Factor that increases heart rate (e.g., epinephrine, caffeine).

Negative Chronotropic Agent

Factor that decreases heart rate (e.g., acetylcholine, beta blockers).

Positive Inotropic Agent

Substance that increases contractility (e.g., Ca²⁺, digitalis).

Negative Inotropic Agent

Substance that decreases contractility (e.g., acidosis, Ca²⁺ channel blockers).

Bradycardia

Resting heart rate below 60 beats/min in adults.

Tachycardia

Resting heart rate above 100 beats/min in adults.

Arrhythmia

Any abnormal heart rhythm.

Fibrillation

Rapid, irregular electrical activity causing ineffective pumping; can be atrial or ventricular.

Heart Block

Impaired transmission through AV node/bundle leading to slowed or absent ventricular activation.

P Wave

ECG deflection representing atrial depolarization.

QRS Complex

ECG deflection representing ventricular depolarization (and hidden atrial repolarization).

T Wave

ECG deflection representing ventricular repolarization.

P-R Interval

Time from onset of atrial depolarization to onset of ventricular depolarization.

Q-T Interval

Time from start of ventricular depolarization to end of ventricular repolarization.

S-T Segment

Flat portion of ECG corresponding to ventricular plateau phase.

Cardiac Cycle

All mechanical events in one heartbeat: atrial systole/diastole followed by ventricular systole/diastole.

Isovolumetric Contraction

Early ventricular systole when pressure rises but all valves are closed; volume constant.

Ventricular Ejection

Phase when rising ventricular pressure opens semilunar valves and blood is expelled.

Isovolumetric Relaxation

Early diastole when ventricles relax, semilunar valves close, and volume is constant.

End-Diastolic Volume (EDV)

Volume of blood in a ventricle at the end of filling (~120 mL).

End-Systolic Volume (ESV)

Volume of blood remaining in a ventricle after contraction (~50 mL).

Ductus Arteriosus

Fetal vessel connecting pulmonary trunk to aorta; becomes ligamentum arteriosum after birth.

Foramen Ovale

Fetal opening between atria allowing blood to bypass lungs; becomes fossa ovalis postnatally.