Cardiovascular System Comprehensive Review

Vocabulary practice flashcards covering anatomical boundaries, physiological mechanisms, histological classifications, biochemical markers, pharmacological agents, and pathological concepts across the Cardiovascular System module.

Sternal Angle Separation Line

An imaginary line extending from the sternal angle anteriorly to the lower border of the $4\text{th}$ thoracic vertebra ($T_4$) posteriorly, separating the superior mediastinum from the inferior mediastinum.

Transverse Pericardial Sinus

A passage inside the pericardial cavity formed during embryological heart tube folding, bounded anteriorly by the pulmonary trunk and ascending aorta, and posteriorly by the superior vena cava, right atrium, and left atrium.

Apex of the Heart

The lowermost, leftmost part of the heart formed entirely by the left ventricle, located at the left $5\text{th}$ intercostal space, $9\,cm$ from the midline.

Moderator Band

A muscular band found in the rough inflow part of the right ventricle that carries conducting fibers from the right bundle branch to the ventricular wall.

Septum Primum

A sickle-shaped embryonic septum that grows from the roof of the common atrium toward the endocardial cushions, bounding the temporary ostium primum.

Anterior Interventricular Artery (LAD)

A major branch of the left coronary artery that descends in the anterior interventricular sulcus to supply both ventricles and the anterior $2/3$ of the interventricular septum.

Atrial Natriuretic Factor (ANF)

A hormone synthesized by atrial myocytes that influences blood pressure by affecting kidney function to promote sodium and water excretion.

Intercalated Discs

Specialized step-like junctional complexes between adjacent cardiac muscle cells containing fasciae adherentes, maculae adherentes (desmosomes), and gap junctions.

Continuous (Type I) Capillaries

Capillaries with an uninterrupted endothelial lining bound by tight junctions (zonula occludentes), requiring transport via pinocytosis or diffusion.

Sinoatrial Node (SAN)

The primary pacemaker of the heart located in the right atrium behind the $SVC$ opening, which spontaneously generates impulses at an intrinsic rate of $90\text{--}110\,\text{impulses/min}$.

Prepotential (Phase 4 of Pacemaker AP)

The slow spontaneous diastolic depolarization in pacemaker cells caused by inward funny current ($I_f$) and transient ($T\text{-type}$) $Ca^{2+}$ entry, carrying the membrane potential from $-60\,mV$ to the firing threshold of $-40\,mV$.

Plateau Phase (Phase 2 of Fast Response AP)

The sustained depolarization phase in ventricular myocytes maintained near $0\,mV$ for about $200\,ms$ by a balance between inward $Ca^{2+}$ current through L-type channels and outward $K^+$ current.

Absolute Refractory Period (ARP)

The period during which cardiac muscle cannot respond to any stimulus because fast $Na^+$ channels are inactivated, lasting through systole and early diastole to prevent muscle tetanization.

Frank-Starling Law of the Heart

The intrinsic mechanism stating that, within physiological limits, the force of myocardial contraction is directly proportional to the initial length of the cardiac muscle fibers (End Diastolic Volume).

AV Nodal Delay

The slow conduction speed ($0.02\text{--}0.05\,m/s$) through the atrioventricular node that allows the atria to complete ventricular filling before ventricular contraction begins.

First Heart Sound ($S_1$)

The low-pitched, soft cardiac sound caused by the sudden closure of the atrioventricular (mitral and tricuspid) valves during the isometric contraction phase.

Incisura (Dicrotic Notch)

A temporary sharp drop in the aortic pressure curve caused by the sudden closure of the aortic valve at the end of ventricular systole.

Bainbridge Reflex

A nervous reflex in which an increase in right atrial pressure and venous return causes a compensatory increase in heart rate to prevent blood stagnation.

Critical Closing Pressure

The internal pressure threshold at which blood flow through a small vessel stops completely and the vessel collapses.

Triple Response of Lewis

A local vascular reaction to heavy skin stroking consisting of a red line (capillary dilation), a flare (arteriolar dilation via axon reflex), and a wheal (localized edema).

Apolipoprotein C-II (Apo C-II)

An apolipoprotein present on chylomicrons and VLDL that serves as a vital cofactor to activate the enzyme lipoprotein lipase (LPL).

Creatine Kinase-MB (CK-MB)

A cardiac-specific enzyme isoenzyme that rises $4\text{--}8\,\text{hours}$ after an acute myocardial infarction, peaks at $24\,\text{hours}$, and returns to baseline within $48\text{--}72\,\text{hours}$.

Cardiac Troponin I (cTnI)

A highly sensitive regulatory protein marker specific for myocardial injury that appears in plasma $4\text{--}6\,\text{hours}$ post-MI, peaks in $8\text{--}28\,\text{hours}$, and remains elevated for $4\text{--}10\,\text{days}$.

Clonidine

A centrally acting $\alpha_2\text{-adrenoceptor}$ agonist that decreases sympathetic outflow to reduce peripheral vascular resistance, known for causing rebound hypertensive crisis if abruptly withdrawn.

Captopril

An Angiotensin-Converting Enzyme (ACE) inhibitor that lowers blood pressure by blocking the formation of Angiotensin II and inhibiting bradykinin breakdown.

Digoxin

A cardiac glycoside that inhibits the myocardial $Na^+/K^+\text{-ATPase}$ pump to increase intracellular $Ca^{2+}$ and contractility, while enhancing vagal tone to slow AV nodal conduction.

Amiodarone

An iodine-containing Class III antiarrhythmic drug that blocks potassium channels to prolong action potential duration, associated with side effects such as pulmonary fibrosis and corneal microdeposits.

Statins (HMG-CoA Reductase Inhibitors)

First-line hypolipidemic drugs that competitively inhibit HMG-CoA reductase to block hepatic cholesterol synthesis, leading to increased clearance of plasma LDL via upregulated LDL receptors.

Sacubitril/Valsartan

An ARNi drug combination consisting of a neprilysin inhibitor and an angiotensin receptor blocker that boosts beneficial natriuretic peptides while suppressing the renin-angiotensin-aldosterone system.

Aschoff Bodies

Pathognomonic granulomatous inflammatory foci in acute rheumatic carditis containing T lymphocytes, plasma cells, and swollen activated macrophages called Anitschkow cells.

Janeway Lesions

Small, painless erythematous macules on the palms and soles characteristic of acute infective endocarditis.

Hypertrophic Cardiomyopathy (HCM)

An autosomal dominant genetic heart disease commonly caused by mutations in the $\beta\text{-myosin}$ heavy chain ($\beta\text{-MHC}$) gene, characterized by massive myocardial hypertrophy and diastolic dysfunction.

Prinzmetal Variant Angina

An atypical form of angina caused by episodic coronary artery vasospasm occurring at rest, independent of physical exertion or increased heart rate.

Streptococcus pyogenes

A Group A $\beta\text{-hemolytic}$ bacterium containing surface M proteins that can trigger post-infectious acute rheumatic fever through molecular mimicry.

Trypanosoma cruzi

The flagellated protozoan parasite transmitted by Reduviid bug feces that causes American trypanosomiasis (Chagas' disease).

Romaña's Sign

Unilateral eyelid edema, conjunctivitis, and ipsilateral pre-auricular lymphadenopathy resulting from a Trypanosoma cruzi infection near the eye.