19.3 Cardiac Cycle

Ventricular systole

-atria relax and ventricles begin to contract -rising ventricular pressure results in the closing of the AV valves -isometric contraction phase (all valves are closed) -ejection phase -ESV

most blood enters the ventricle during a. atrial systole b. atrial diastole c. ventricular systole d. isovolumic contraction

B. atrial diastole

ventricular systole is represented by what part of the ECG?

QRS complex

two audible heart sounds

S1 and S2

how do fluids typically move?

according to pressure gradient. they move from regions that are higher in pressure to regions that are lower in pressure

ventricular relaxation immediately follows a. atrial depolarization b. ventricular repolarization c. ventricular depolarization d. atrial repolarization

b. ventricular repolarization

what happens when the blood pressure in the ventricles drops below that of the atria?

blood flows from the atria into the ventricles, opening the tricuspid and mitral valves. As pressure drops within the ventricles, blood flows from the major veins into the relaxed atria and from there into the ventricles.

SL valves during ventricular ejection phase

blood is pumped from the heart, pushing open the pulmonary and aortic valves

What marks the end of the cardiac cycle?

both chambers are in diastole, the atrioventricular valves are open, and the semilunar valves remain closed.

the first heart sound represents which portion of the cardiac cycle? a. atrial systole b. ventricular systole c. closing of the AV valves d. closing of the semilunar valves

c. closing of the AV valves

contraction of the atria follows_

depolarization

ventricular systole follows__

depolarization of the ventricles

in (late ventricular diastole) as the ventricular muscle relaxes what happens to the BP within the ventricles?

drops even further, eventually lower than that of the atria

isovolumic ventricular relaxation phase/ isovolumetric ventricular relaxation phase

early phase of ventricular diastole

what does this increase in pressure cause blood to do?

flow back toward the atria, closing the tricuspid and mitral valves.

when the heart chambers are relaxed (diastole), what does the blood do?

flows into the atria from the veins, which are higher in pressure

(beginning of cardiac cycle) blood flows into the left atrium from

four pulmonary veins

isovolumic contraction aka isovolumetric contraction

initial phase of ventricular contraction in which tension and pressure in the ventricle increase, but no blood is pumped or ejected from the heart

when atrial systole occurs, where does the blood go?

into the ventricles

what happens to the blood when pressure within the ventricles drops below pressure in both the pulmonary trunk and aorta?

it flows back toward the heart, producing the dicrotic notch seen in BP tracings.

atrioventricular valves at the beginning of the cardiac cycle

open so that blood flows unimpeded from the atria and into the ventricles.

atrial contraction is represented by what wave of the ECG?

p wave

pressure generated in the left ventricle vs right ventricle

pressure generated by the left ventricle will be appreciably greater than the pressure generated by the right ventricle, since the existing pressure in the aorta will be so much higher. Both ventricles pump the same amount of blood

what happens to the pressure as the atrial muscles contract from the superior portion of the atria toward the AV septum?

pressure rises within the atria and blood is pumped into the ventricles through the open AV valves

what happens as blood flows into the atria?

pressure will rise, so the blood will initially move passively from the atria into the ventricles

semilunar valves

pulmonary and aortic valves

what does blood do during ventricular systole?

pumps to the pulmonary trunk from the right ventricle and into the aorta from the left ventricle

atria and ventricles at the beginning of the cardiac cycle

relaxed/diastole

volume of blood in the ventricles at this stage

remain constant since blood is not being ejected from the ventricles

diastole follows __

repolarization of the ventricles

S4

results from the contraction of the atria pushing blood into a stiff or hypertrophic ventricle, indicating failure of the left ventricle

late ventricular diastole

second phase of ventricular diastole.

ventricular ejection phase

second phase of ventricular systole. the contraction of the ventricular muscle has raised the pressure within the ventricle to the point that it is greater than the pressures in the pulmonary trunk and the aorta

Stroke Volume

the amount of blood the ventricles pump.

what happens in both cases in the heart sounds as the valves close?

the openings within the atrioventricular septum guarded by the valves will become reduced, and blood flow through the opening will become more turbulent until the valves are fully closed.

systole

the period of contraction that the heart undergoes while it pumps blood into circulation

S2

the sound of the closing of the semilunar valves during ventricular diastole (dub/second heart sound)

(beginning of the cardiac cycle) blood is flowing into the right atrium from

the superior and inferior venae cavae and the coronary sinus

what happens to the SL valves

they close to prevent backflow into the heart

S3

third heart sound that is rarely heard in healthy individuals

quiescent period

total heart relaxation

S3 can be heard in what individuals?

youth, some athletes, pregnant women, CHF

End systolic Volume (ESV)

amount of blood remaining in each ventricle following systole

early phase of ventricular diastole

ventricular muscle relaxes, pressure on the remaining blood within the ventricle begins to fall.

what wave is ventricular diastole represented by?

T wave

murmer

an unusual sound coming from the heart that is caused by the turbulent flow of blood

semilunar valves at the beginning of the cardiac cycle

closed, preventing backflow of blood into the right and left ventricles from the pulmonary trunk on the right and the aorta on the left

state of AV valves in early Ventricular diastole

closed. so there is no change in the volume of blood in the ventricle

the cardiac cycle consists of a distinct relaxation and contraction phase. Which term is typically used to refer ventricular contraction while no blood is being ejected? a. systole b. diastole c. quiescent d. isovolumic contraction

d. isovolumic contraction

what happens to the BP as the muscles in the ventricle contract?

initially, the blood pressure within the chamber rises, but it's not yet high enough to open the semilunar valves and be ejected from the heart. however, BP quickly rises above that of the atria that are now relaxed in diastole

end diastolic volume (EDV) aka preload

the amount of blood in the ventricles at the end of atrial systole just prior to ventricular contraction

diastole

the period of relaxation that occurs as the chambers fill with blood

cardiac cycle

the period of time that begins with contraction of the atria and ends with ventricular relaxation

S1

the sound created by the closing of the AV valves during ventricular contraction (lub/first heart sound)

S3 sound causes

the sound of blood flowing into the atria, blood sloshing back and forth in the ventricle, or even tensing of the chordae tendineae

atrioventricular valves

tricuspid and mitral valves