Lecture 11 (Part 1)

Systole definition

Heart contraction (chambers eject/pump blood)

Diastole definition

Heart relaxation (chambers fill up with blood)

5 phases of cardiac cycle

Atrial contraction, isovolumetric contraction, ventricular ejection, isovolumetric relaxation, ventricular filling

Atrial systole involves (1 feature)

Atrial contraction

Ventricular systole involves (2 features)

Isovolumetric contraction, ventricular ejection

Ventricular diastole involves (2 features)

Isovolumetric relaxation, ventricular filling

Sequence of cardiac cycle

Atrial systole and diastole, followed by ventricular systole and diastole

Cardiac cycle definition

Blood flow through heart during one complete heartbeat

End diastolic volume definition

amount of blood in the ventricle after it fills up with blood (after diastole)

End systolic volume definition

amount of blood that remains in the ventricle after it ejects blood (after systole)

AV valves

tricuspid and bicuspid/mitral valves

Semilunar valves

aortic and pulmonary valves

Stroke volume definition

volume of blood ejected from each ventricle during systole

Stroke volume formula

Stroke Volume = EDV - ESV

All valves are _ during isovolumetric contraction and isovolumetric relaxation

Closed

Which valves are open during ventricular ejection?

Semilunar valves

Which valves are open during ventricular filling?

AV valves

Which valves are open during atrial contraction?

AV valves

What happens during isovolumetric contraction (beginning of ventricular systole)?

-Ventricular pressure increases

-No valves are open, so no ejection of blood yet

-Blood volume is at EDV

What happens during ventricular ejection?

-Ventricular pressure exceeds aorta and pulmonary trunk pressures

-Blood is ejected out of ventricles and into the aorta and pulmonary trunk

What happens during isovolumetric relaxation (beginning of ventricular diastole)?

-Ventricular pressure decreases

-No valves are open, so no filling of blood yet

-Blood volume is at ESV

What happens during ventricular filling?

-Ventricular pressure decreases below atrial pressure

-Blood leaves the atrium and fills the ventricles

Two sounds (lub-dup) associated with closing of heart valves

S1 and S2

S1 heart sound represents

Closing of AV valves

S2 heart sound represents

Closing of semilunar valves

Two sounds associated with heart murmurs

S3 and S4

S3 heart sound represents

Volume problem

Example of volume problem for S3 heart sound (1 feature)

Congestive heart failure

S4 heart sound represents

Pressure problem

Example of pressure problem for S4 heart sound (2 features)

Hypertension, restrictive cardiomyopathy

Cardiac output definition

amount of blood pumped out by each ventricle per minute

Cardiac output formula

Cardiac Output = Heart Rate x Stroke Volume

3 factors that affect stroke volume

Preload, contractility, afterload

Preload vs. Afterload

-Preload = volume and stretch

-Afterload = pressure and resistance

Increased stroke volume involves _ preload, _ contractility, and _ afterload

Increased; increased; decreased

Preload definition

the volume of blood in the ventricles at the end of diastole that stretches the cardiac muscle fibers

Afterload definition

the resistance or pressure the ventricles must overcome in the blood vessels to open the semilunar valves and eject blood during systole