Chapter 17: Function of the Heart Practice Flashcards

Vocabulary-style flashcards covering the physiological mechanisms of heart function, cardiac output calculations, autonomic regulation, and heart failure phenotypes.

Diastole

The phase of the cardiac cycle where relaxed ventricles receive blood.

Systole

The phase of the cardiac cycle where the heart muscle contracts, creating pressure and ejecting blood.

Atrial Kick

The final, variable portion of ventricular filling added by atrial contraction; it can be lost in conditions like atrial fibrillation.

S1

The first heart sound, occurring when ventricular pressure exceeds atrial pressure and the AV valves close.

Isovolumetric Contraction

A phase where all heart valves are closed and pressure rises while ventricular volume stays constant.

S2

The second heart sound, caused by the closure of the aortic and pulmonary semilunar valves.

Chordae and Papillary Muscles

Structures that prevent AV valve prolapse during systole but do not pull the leaflets open.

Positive Chronotropy

An effect that increases heart rate by increasing SA-node firing.

Positive Dromotropy

An effect that speeds up conduction, particularly through the AV node.

Positive Inotropy

An effect that strengthens the intrinsic force of the ventricular squeeze.

Positive Lusitropy

An effect that speeds up cardiac relaxation to support filling at higher heart rates.

Vagus Nerve

The nerve responsible for parasympathetic (vagal) activity that slows the SA and AV nodes via acetylcholine ($ACh$).

Atropine

A medication that blocks muscarinic effects and may raise heart rate in symptomatic bradycardia.

Cardiac Output ($CO$)

The volume of blood one ventricle pumps each minute, calculated as $CO = HR \times SV$.

Stroke Volume ($SV$)

The volume of blood ejected per beat, calculated as $SV = EDV - ESV$.

Preload

The amount of ventricular stretch present at end-diastole, influenced by venous return and fluid volume.

Afterload

The load the ventricle must overcome to eject blood, such as systemic vascular resistance ($SVR$) or arterial impedance.

Contractility

The intrinsic strength of the heart's squeeze independent of loading conditions.

Frank-Starling Law

The principle that increased venous return leads to increased end-diastolic stretch, which usually increases contraction force and stroke volume.

Ejection Fraction ($EF$)

The percentage of end-diastolic volume ejected with each beat, calculated as $EF = SV \times EDV^{-1} \times 100$.

Cardiac Reserve

The ability of the heart to increase output during periods of increased demand, such as physical activity.

Left-Sided Heart Failure

A condition where fluid backs up into the lungs, cause pulmonary congestion symptoms like dyspnea, crackles, and orthopnea.

Right-Sided Heart Failure

A condition where fluid backs up into the systemic veins, causing cues like jugular venous distension ($JVD$), edema, and hepatomegaly.

Pink Frothy Sputum

A severe acute sign of pulmonary edema which is an airway-breathing emergency.

Four Disease-Modifying Pillars

The standard chronic medication therapy for HFrEF, consisting of: 1) ARNI or ACEI/ARB, 2) beta-blocker, 3) MRA, and 4) SGLT2i.