cardiac cycle

Question 1

cardiac cycle is defined as

Answer 1

the cardiac events initiated by the P wave in the ecg and continuing until the next P wave.

Question 2

Phase 1

Answer 2

Atrial systole, ventricular diastole

Question 3

is atrial contraction essential for ventricular filling

Answer 3

no, only accounts for about 10% of LV filling when HR is low but is important during exercise

Question 4

during phase 1 atrial systole, is the AV valve open or closed

Answer 4

open

Question 5

during phase 1 atrial systole, are the aortic and pulmonic valves open or closed?

Answer 5

closed

Question 6

what does the p wave represent

Answer 6

depolarization of the atria.

Question 7

what does the a wave represent

Answer 7

atrial contraction, pressures within atrial chambers increase.

Question 8

at the end of phase 1, ventricular volumes are

Answer 8

maximal. (end diastolic volume) ~120ml

Question 9

Phase 2

Answer 9

isovolumetric contraction. systole.

Question 10

what is special about the valves in phase 2

Answer 10

all are closed

Question 11

what causes the x-descent on the atrial tracing

Answer 11

when atrial contraction is complete, atrial pressure begins to fall. this causes a slight pressure gradient reversal across the AV valves. as the pressure falls within the atria, the AV valves float upward before closure.

Question 12

Phase 3

Answer 12

(systole)rapid ejection

Question 13

phase 3 aortic and pulmonic valves are

Answer 13

open

Question 14

phase 3 AV valves are

Answer 14

closed

Question 15

why does ejection occur?

Answer 15

total energy of the blood in the ventricles exceeds the total energy of the blood in the aorta and PA. an aery gradient is present.

Question 16

maximal outflow velocity is reached

Answer 16

early in the ejection phase

Question 17

what heart sounds are typically heart during ejection?

Answer 17

none. the opening of healthy heart valves is silent

Question 18

x’ descent

Answer 18

occurs as the base of the atria are pulled downward, expanding the atrial chambers (decreasing initial atrial pressure)

Question 19

what do atria do in phase 3

Answer 19

fill with blood from respective venous inflow tracts. volume is increasing

Question 20

phase 4

Answer 20

(systole) reduced ejection

Question 21

during phase 4, aortic and pulmonic valves are

Answer 21

open

Question 22

during phase 4, AV valves are

Answer 22

closed

Question 23

what does the T wave represent

Answer 23

ventricular repolarization

Question 24

phase 5

Answer 24

isovolumic relaxation. (diastole)

Question 25

phase 5 valves are?

Answer 25

all closed

Question 26

what causes the second heart sound

Answer 26

closure of aortic and pulmonic valves (a before p)

Question 27

incisura (dicrotic notch) represents

Answer 27

aortic / pulmonic valve closure

Question 28

pressure rapidly falls in the ventricle, but aortic and PA pressure..

Answer 28

is not abrupt bc of potential energy in their elastic walls and because systemic and pulmonic vascular resistances impede the flow of blood into distributing arteries of the systemic and pulmonary circulations.

Question 29

why do ventricular volumes remain constant in phase 5?

Answer 29

because all valves are closed

Question 30

End-Systolic volume (ESV)

Answer 30

the residual volume of blood that remains in the ventricle.

Question 31

what is the ESV in the LV?

Answer 31

50ml

Question 32

stroke volume

Answer 32

the difference between end diastolic volume and end systolic volume.

Question 33

what is the approx stroke volume in the ventricle

Answer 33

70ml

Question 34

phase 6

Answer 34

rapid ventricular filling. diastole

Question 35

which valves are open in phase 6

Answer 35

AV valves

Question 36

which valves are closed in phase 6

Answer 36

aortic and pulmonic

Question 37

what contributes to rapid, passive filling of the ventricles?

Answer 37

the ventricles are still relaxing, causing pressures to still fall within them. atrial volumes are maximal just prior to AV valve opening.

Question 38

what does the v-wave represent

Answer 38

peak of the atrial pressure just before the AV valve opens

Question 39

what is y descent

Answer 39

opening of the AV valve that causes a rapid fall in atrial pressure

Question 40

what sounds do AV valves make as they open

Answer 40

none

Question 41

s3

Answer 41

may occur during rapid filling. tensing of the chord tendinae and AV ring. pathological in adults and often associated with ventricular dilation.

Question 42

phase 7

Answer 42

reduced ventricular filling (diastole)

Question 43

phase 7 which valves are open

Answer 43

AV valves

Question 44

phase 7 which valves are closed

Answer 44

aortic and pulmonic

Question 45

during what phase is ventricular filling nearing completion

Answer 45

7

Question 46

as the ventricles fill with blood they become

Answer 46

less compliant (stiff) and pressures rise

Question 47

without compensatory mechanisms, the cycle length reduction in higher heart rates would cause

Answer 47

less ventricular filling

Question 48

what phases are part of ventricular systole

Answer 48

2 3 4

Question 49

what phases are part of ventricular diastole

Answer 49

1 5 6 7

Question 50

what causes heart sounds

Answer 50

closing of valves

Question 51

what causes the first heart sound

Answer 51

closure of AV valves

Question 52

during which phase is the majority of blood ejected from the LV

Answer 52

phase 3 rapid ejection

Question 53

during which phase does most of the filling of the LV occur

Answer 53

6 rapid ventricular filling

Question 54

how much does atrial kick usually contribute to ventricular filling

Answer 54

10%

Question 55

if a person is tachycardia,how much does atrial kick contribute

Answer 55

up to 40%of ventricular filling

Question 56

during A-fib, what happens to the contribution of atrial contraction to ventricular filling

Answer 56

it is lost, leading to inadequate filling.