Cardiac Cycle

Question 1

what are the two phases the heart alternates between?

Answer 1

the filling phase and the emptying phase

Question 2

when do cardiac valves open and close?

Answer 2

when upstream pressure exceeds downstream pressure and closes when downstream pressure exceeds upstream pressure, the movement of valve leaflets can be detected by ECG

Question 3

can heart sounds be heard? if so, how

Answer 3

yes, heart sounds can be heard with a stethoscope

Question 4

what sounds can the stethoscope detect?

Answer 4

regurgitation and stenosis

Question 5

what is regurgitation?

Answer 5

leaks in the valves that permit jets of blood to flow backward across the valvular orifice

Question 6

what is stenosis?

Answer 6

narrowing of the valve opening forcing the blood to pass through a narrower space

Question 7

During certain parts of the cardiac cycle, blood passing through either regurgitant or stenotic lesions makes characteristic sounds that are called?

Answer 7

murmurs

Question 8

what are the four phases the cardiac cycle can be divided into?

Answer 8

inflow phase
isovolumetric contraction
outflow phase
isovolumetric relaxation

Question 9

what is the inflow phase?

Answer 9

The inlet valve is open and the outlet valve is closed

Question 10

what is isovolumetric contraction?

Answer 10

Both valves are closed, with no blood flow.

Question 11

what is outflow phase?

Answer 11

The outlet valve is open and the inlet valve is closed

Question 12

what is isovolumetric relaxation?

Answer 12

Both valves are closed, with no blood flow

Question 13

pressure differences are larger on the left than on the right, T/F?

Answer 13

true

Question 14

during the cardiac cycle, what is happening during the inflow phase?

Answer 14

the left or right ventricle is filling due to pressure difference between the atria and ventricle and gravitational forces

(Diastole)

Question 15

during the cardiac cycle, what is happening during isovolumetric contraction phase?

Answer 15

both aortic and bicuspid valves are closed for the left/right side, pressure gradient building

(Systole)

Question 16

during the cardiac cycle, what is happening during the outflow phase?

Answer 16

blood is squeezed into pulmonary valves

Systole

Question 17

during the cardiac cycle, what is happening during the isovolumetric relaxation phase?

Answer 17

both valves are closed, ventricles are not receiving blood from the atria, empty (decreasing in pressure so they can receive blood from the atria)

(Diastole)

Question 18

describe the pressure difference on the left side of the heart?

Answer 18

before the mitral valve closes the pressures between the left ventricle and left atrium are similar. Both pressures go up as left atrium squeezes toward the end of diastolic phase before the systole starts, emptying its chamber. Mitral valve starts to close as the ventricular pressure climbs again signifying the emptying of the left atrium into the left ventricle. Note time delay before opening of mitral and aortic valves, this is found in the isovolumetric contraction area and pressure is building in the left ventricle trying to reach systemic pressure like in the aorta. Once these pressures are meet (aortic pressure matching with ventricular pressure) Aortic valve opens, blood begins emptying (ventricular ejection) into the Aorta further increasing the pressure. Both pressures decrease down to baseline indicating isovolumetric relaxation with the closing of the aortic valve and opening of the Mitral valve, then it begins again

Question 19

describe the pressure difference on the right side of the heart?

Answer 19

venous system is filling right atria until 10-15 mmHg is reached, pressure in right ventricle matches pressure with right atrium and as tricuspid valve closes, the right atria finishes squeezing itself and so isovolumetric contraction can occur, not so much pressure is required so tricuspid valve closes and pulmonic valve opens we enter ventricular ejection and then pulmonic valve closes and tricuspid valve opens indicating isovolumetric relaxation

Question 20

how much pressure does it generally take to fill the ventricle from the atria?

Answer 20

10-15 mmHg

Question 21

what indicates atrial contraction on the ECG?

Answer 21

P wave is the atrial contraction or depolarization, which causes blood to enter the left ventricle.

Question 22

what indicates ventricular depolarization or isovolumetric contraction on the ECG ?

Answer 22

ventricular depolarization

Question 23

why is jugular venous pressure important?

Answer 23

to better understand the functioning of the heart, like right sided heart failure

Question 24

the mitral and tricuspid valves correspond to what s sound?

Answer 24

S1

Question 25

the aortic and pulmonary valves correspond to what s sound

Answer 25

S2

Question 26

how is S1 produced?

Answer 26

vibrations resulting from sudden tension in the AV valves and the adjacent ventricular walls produce S1

Question 27

how is S2 produced?

Answer 27

vibrations of the large vessel walls and columns of blood produce S2 following closure of the semilunar valves. These vibrations propagate through adjacent tissues to the chest wall, where one can normally hear the first and second heart sounds through a stethoscope.

Question 28

which heart sound is more prominent?

Answer 28

S1 is usually stronger, longer, and of lower frequency than S2.

Question 29

in terms of jugular venous pressure changes caused by the cardiac cycle, what is the a peak?

Answer 29

is caused by the contraction of the right atrium

Question 30

in terms of jugular venous pressure changes caused by the cardiac cycle, what is the c peak?

Answer 30

reflects the pressure rise in the right ventricle early during systole, and the resultant bulging of the tricuspid valve - which has just closed - into the right atrium.

Question 31

in terms of jugular venous pressure changes caused by the cardiac cycle, what is the v peak?

Answer 31

related to filling of the right atrium against a closed tricuspid valve, which causes right atrial pressure to rise. As the tricuspid valve opens, the v peak begins to wane.

Question 32

what are the three peaks in the jugular pulse wave?

Answer 32

a,c,v