Heart Anatomy and Cardiac Function (NCMB312)

Vocabulary flashcards covering heart anatomy, layers, valves, coronary circulation, blood flow, conduction system, cardiac function, auscultation landmarks, common valve disorders, and risk factors/complications.

Heart

Cone-shaped hollow muscular organ in the center of the chest (mediastinum) that pumps blood through the circulatory system; weighs about 300 g and is the size of a fist; ~60 mL of blood per beat (~5 L/min).

Mediastinum

Central compartment of the thoracic cavity between the lungs that houses the heart.

Right Atrium

Receiving chamber for deoxygenated blood from the body via the superior and inferior vena cavae (and coronary sinus); transfers blood to the right ventricle.

Right Ventricle

Pumps deoxygenated blood to the lungs via the pulmonary artery.

Left Atrium

Receives oxygenated blood from the lungs via the pulmonary veins and passes it to the left ventricle.

Left Ventricle

Pumps oxygen-rich blood to the rest of the body; the strongest chamber.

Atrioventricular Valve

Valves between atria and ventricles that prevent backflow; include the tricuspid and mitral (bicuspid) valves.

Tricuspid Valve

AV valve between the right atrium and right ventricle with three cusps.

Mitral (Bicuspid) Valve

AV valve between the left atrium and left ventricle with two cusps; prevents backflow.

Semilunar Valves

Valves with half-moon cusps that prevent backflow from arteries into the ventricles; include pulmonic and aortic valves.

Pulmonic Valve

Semilunar valve between the right ventricle and the pulmonary artery; opens to send blood to the lungs.

Aortic Valve

Semilunar valve between the left ventricle and the aorta; opens to send blood to systemic circulation.

Coronary Arteries

Arteries that supply arterial blood to the heart; originate from the aorta above the aortic valve.

Right Coronary Artery (RCA)

Supplies right atrium, right ventricle, portion of septum, inferior left ventricle, and the SA and AV nodes; gives rise to Right Marginal Artery and Posterior Descending Artery.

Left Coronary Artery (LCA)

Supplies the left ventricle; branches include Left Anterior Descending (LAD) and Circumflex (Cx).

Right Marginal Artery

Branch of the RCA supplying the right ventricle margin.

Posterior Descending Artery (PDA)

Branch of the coronary artery system supplying the posterior portion of the heart.

Left Anterior Descending Artery (LAD)

Branch of the LCA that supplies the anterior wall of the left ventricle and the anterior interventricular septum.

Circumflex Artery

Branch of the LCA that supplies the left atrium, lateral and posterior left ventricle, and part of the interventricular septum.

Coronary Sinus

A venous channel that returns blood from the heart muscle to the right atrium.

Myocardium

Middle muscular layer of the heart wall; made of cardiac myocytes; responsible for contraction.

Epicardium

Outer layer of the heart wall; contains mesothelial cells, fat, and connective tissue.

Endocardium

Inner layer of the heart wall; composed of simple squamous epithelium.

Pericardium

Thin sac enclosing the heart; provides lubrication, protects from infection, and prevents overexpansion; contains about 5–20 mL of fluid.

Chordae Tendineae

Tendinous cords that anchor valve leaflets to papillary muscles to prevent prolapse and backflow.

Papillary Muscles

Muscles attached to the ventricular walls; connect to the AV valves via chordae tendineae.

Blood Flow Through the Heart

Normal sequence: SVC/IVC/Coronary Sinus → Right Atrium → Tricuspid Valve → Right Ventricle → Pulmonic Valve → Pulmonary Artery → lungs → Pulmonary Veins → Left Atrium → Mitral Valve → Left Ventricle → Aortic Valve → Aorta → Systemic circulation.

Automaticity

Ability of cardiac tissue to initiate electrical impulses spontaneously.

Excitability

Ability to respond to a stimulus by initiating a cardiac impulse.

Conductivity

Ability to transmit an electrical impulse from one cell to another.

Contractility

Ability of cardiac muscle to contract in response to an impulse.

Refractoriness

Inability to respond to a new stimulus while the heart is still contracting.

Cardiac Output

Volume of blood ejected from the left ventricle per minute; normally about 5 L/min at rest; CO = Stroke Volume × Heart Rate.

Stroke Volume

Amount of blood ejected by the left ventricle per beat; ~60–130 mL (average ~70 mL); EDV − ESV; influenced by preload, contractility, afterload.

Heart Rate

Number of heartbeats per minute; resting typical 60–80 bpm.

End Diastolic Volume (EDV)

Volume of blood in the ventricle at the end of diastole (filling).

End Systolic Volume (ESV)

Volume of blood in the ventricle at the end of systole (contraction).

Ejection Fraction (EF)

EF = (SV/EDV) × 100%; normal about 55–65%.

Cardiac Index

CO expressed per square meter of body surface area; normal range 2.4–4.0 L/min/m2.

Body Surface Area (BSA)

Estimate of body surface used for dosing and index calculations; formula provided: (Height in cm × Weight in kg)/3600.

Frank-Starling Law

More preload stretches ventricular fibers, leading to a stronger contraction and greater stroke volume.

Preload

Degree of myocardial fiber stretch before contraction (filling pressure).

Afterload

Tension the ventricle must develop to eject blood; resistance to ejection.

Inotropy

Change in the force of cardiac muscle contraction (inotropic state) independent of preload.

Systolic Blood Pressure

Pressure in arteries during ventricular contraction.

Diastolic Blood Pressure

Pressure in arteries during ventricular relaxation.

Apex

5th intercostal space at the left midclavicular line; the apex of the heart; site of the apical impulse.

S1 (Lub)

Closure of the AV valves; best heard at the apex; marks beginning of ventricular systole.

S2 (Dub)

Closure of the semilunar valves; best heard at the base.

Aortic Area

2nd intercostal space at the right sternal border; auscultation area for the aortic valve.

Pulmonic Area

2nd/3rd intercostal spaces at the left sternal border; auscultation area for the pulmonic valve.

Erb’s Point

3rd intercostal space at the left sternal border; auscultation area.

Tricuspid Area

4th–5th intercostal space at the left lower sternal border; auscultation area for the tricuspid valve.

Mitral Valve Prolapse (Barlow syndrome)

Prolapse of the mitral valve leaflets; can cause regurgitation; sometimes treated with beta-blockers.

Regurgitation

Backflow of blood due to incomplete valve closure; can cause murmurs and increased cardiac workload.

Murmurs

Audible sounds from turbulent blood flow due to valve abnormalities (prolapse, regurgitation, stenosis).

Stenosis

Valve leaflets become thickened or stiff; narrowed opening causing reduced blood flow and lower stroke volume.

Atresia

Valve or orifice not formed; blocks blood flow between chambers; may cause cyanosis.

Congenital Heart Disease

Birth defects of the heart present at birth.

Risk Factors

Birth defects, older age, infections affecting the heart, history of heart disease, high blood pressure, high cholesterol, diabetes.

Complications

Possible outcomes such as heart failure, blood clots, stroke, arrhythmias, and death.