Lecture 4

Flashcards covering key vocabulary from the lecture notes on the cardiac cycle, pressure-volume curves, heart sounds, autonomic innervation, and cardiac output.

Systole

Ventricular contraction and ejection of blood.

Diastole

Ventricular relaxation and filling of the ventricles with blood.

Cardiac cycle length

The period of time from the beginning of one heartbeat to the beginning of the next.

Isovolumetric ventricular contraction

Ventricles contract, all heart valves closed, blood volume in ventricles remains constant, pressures rise.

Ventricular ejection phase

Pressure generated by the ventricles exceeds the pressure in the artery, opening the semilunar valves and allowing ventricular ejection.

Stroke volume

The volume of blood ejected from each ventricle during systole.

Isovolumetric ventricular relaxation

All heart valves closed, blood volume remains constant, pressures drop.

Ventricular filling

AV valves open, blood flows into ventricles from atria.

Passive ventricular filling

Ventricles receive approximately 70% of their blood volume.

Atrial contraction (atrial kick)

Completes ventricular filling.

Cardiac cycle

The rhythmical contraction and relaxation of the heart’s chambers coordinated by electrical activity.

End-diastolic volume (EDV)

The amount of blood in each ventricle at the end of ventricular diastole.

End-systolic volume (ESV)

The amount of blood in each ventricle at the end of ventricular systole.

Stroke volume (SV)

The volume of blood pumped out of each ventricle during systole; calculated as SV = EDV - ESV.

First heart sound (lub)

Caused by closure of the AV valves at the beginning of isovolumetric ventricular contraction.

Second heart sound (dub)

Caused by closure of the semilunar valves and signifies the onset of ventricular diastole.

Laminar flow

Smooth concentric layers of blood moving in parallel down the length of a blood vessel.

Stenotic valve

A valve in which the leaflets do not open completely, causing turbulent blood flow and a murmur.

Insufficient valve

A valve that does not close completely, causing blood to flow backwards and produce a murmur.

Sympathetic innervation

Innervates the entire heart, including atria, ventricles, SA node, and AV node; releases norepinephrine.

Parasympathetic innervation

Innervates the atria, SA node, and AV node; releases acetylcholine.

Cardiac output (CO)

The amount of blood pumped by each ventricle in one minute; CO = HR x SV.

Resting autonomic tone

Active at a steady background level, influencing heart rate.

Sympathetic stimulation of the SAN

Increase the slope of the pacemaker potential causing a faster depolarization to threshold.

Parasympathetic stimulation of the SAN

Decreases the slope of the pacemaker potential causing a slower depolarization to threshold.

SAN

stands for sinoatrial node (which is the heart's natural pacemaker), it's a group of conducting myocytes in the heart responsible for initiating the heart