ch26;Structure and Function of the Cardiovascular System

Vocabulary flashcards covering the key anatomy, electrical events, hemodynamic formulas, and physiological mechanisms of the cardiovascular system from Chapter 25 Pathophysiology notes.

Right Heart

The functional side of the heart that receives deoxygenated blood from the body and pumps it into the low-pressure pulmonary circuit toward the lungs.

Left Heart

The functional side of the heart that receives oxygenated blood from the lungs and pumps it into the high-pressure systemic circuit toward the body.

Atria

The receiving chambers of the heart that collect blood returning from the body or lungs before it enters the ventricles.

Ventricles

The primary pumping chambers of the heart that contract to eject blood into the pulmonary and systemic circulations.

Heart Blood Flow Pathway

The sequential flow of blood through the cardiac chambers and valves: Body $\rightarrow$ Right Atrium $\rightarrow$ Tricuspid Valve $\rightarrow$ Right Ventricle $\rightarrow$ Pulmonic Valve $\rightarrow$ Lungs $\rightarrow$ Left Atrium $\rightarrow$ Mitral Valve $\rightarrow$ Left Ventricle $\rightarrow$ Aortic Valve $\rightarrow$ Body.

Systole

The contractile phase of the cardiac cycle in which ventricles contract, AV valves close (producing S1), semilunar valves open, and blood is ejected from the ventricles.

Diastole

The relaxation phase of the cardiac cycle in which ventricles relax, semilunar valves close (producing S2), AV valves open, and most ventricular filling occurs.

S1 Heart Sound

The first heart sound ("lub"), produced by the closure of the AV valves (tricuspid and mitral) at the beginning of ventricular systole.

S2 Heart Sound

The second heart sound ("dub"), produced by the closure of the semilunar valves (pulmonic and aortic) at the start of ventricular diastole.

P Wave

The ECG wave representing atrial depolarization, which is followed by atrial contraction ("atrial kick") that contributes approximately $10-20\%$ of ventricular filling.

QRS Complex

The ECG waveform representing ventricular depolarization, which initiates ventricular contraction and the start of systole.

T Wave

The ECG wave representing ventricular repolarization, during which the ventricles prepare to relax.

End-Diastolic Volume (EDV)

The total volume of blood in a ventricle at the end of filling (diastole), approximately $120\,mL$ in a normal heart.

Stroke Volume (SV)

The volume of blood ejected from the ventricle with each contraction beat, calculated as $\text{SV} = \text{EDV} - \text{ESV}$ (typically about $70\,mL$).

Ejection Fraction (EF)

The percentage of end-diastolic blood volume ejected with each beat, calculated as $\text{EF} = \text{SV} \div \text{EDV}$ (normal left ventricular EF is approximately $55-75\%$).

Cardiac Output (CO)

The volume of blood pumped by the heart per minute, calculated using the core equation $\text{CO} = \text{HR} \times \text{SV}$ (resting adult normal is approximately $4-6\,L/min$).

Preload

The degree of ventricular filling and myocardial stretch present at the end of diastole prior to contraction, driven largely by venous return.

Afterload

The resistance that the ventricle must overcome to eject blood into circulation, with systemic blood pressure serving as the major afterload for the left ventricle.

Contractility

The intrinsic strength and force of myocardial contraction independent of ventricular filling volume, strongly influenced by calcium.

Frank-Starling Law

The physiological principle stating that increased venous return increases ventricular filling (preload) and myocardial fiber stretch, which increases force of contraction and stroke volume within physiologic limits.

Pulmonary Circulation

The low-pressure, low-resistance circulatory circuit routing deoxygenated blood from the right ventricle to the lungs for gas exchange and back to the left atrium.

Systemic Circulation

The high-pressure, high-resistance circulatory circuit routing oxygenated blood from the left ventricle through the body for tissue perfusion and back to the right atrium.

Resistance

The opposition to blood flow through vascular beds, primarily controlled by arterioles.

Vasoconstriction

The narrowing of blood vessel radius, which increases resistance and decreases blood flow.

Vasodilation

The widening of blood vessel radius, which decreases resistance and increases blood flow.

Arterioles

Small resistance vessels in the arterial tree that regulate blood flow into capillaries and serve as major determinants of systemic vascular resistance.

Veins

Low-pressure, high-compliance blood vessels equipped with valves and skeletal muscle pump support that return blood to the heart and serve as a blood reservoir.

Capillaries

Single-cell-thick exchange vessels with slow blood flow that link the arterial and venous circulations to support gas and nutrient exchange.

Capillary Hydrostatic Pressure

The fluid pressure inside capillaries that pushes fluid out into the interstitial space, elevated by increases in venous pressure.

Colloid Osmotic Pressure

The osmotic pull created by plasma proteins (primarily albumin) that pulls fluid into the capillary from the interstitial space.