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Flashcards in cardiac cycle Deck (56):
1

cardiac cycle is defined as

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

2

Phase 1

Atrial systole, ventricular diastole

3

is atrial contraction essential for ventricular filling

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

4

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

open

5

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

closed

6

what does the p wave represent

depolarization of the atria.

7

what does the a wave represent

atrial contraction, pressures within atrial chambers increase.

8

at the end of phase 1, ventricular volumes are

maximal. (end diastolic volume) ~120ml

9

Phase 2

isovolumetric contraction. systole.

10

what is special about the valves in phase 2

all are closed

11

what causes the x-descent on the atrial tracing

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.

12

Phase 3

(systole)rapid ejection

13

phase 3 aortic and pulmonic valves are

open

14

phase 3 AV valves are

closed

15

why does ejection occur?

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.

16

maximal outflow velocity is reached

early in the ejection phase

17

what heart sounds are typically heart during ejection?

none. the opening of healthy heart valves is silent

18

x' descent

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

19

what do atria do in phase 3

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

20

phase 4

(systole) reduced ejection

21

during phase 4, aortic and pulmonic valves are

open

22

during phase 4, AV valves are

closed

23

what does the T wave represent

ventricular repolarization

24

phase 5

isovolumic relaxation. (diastole)

25

phase 5 valves are?

all closed

26

what causes the second heart sound

closure of aortic and pulmonic valves (a before p)

27

incisura (dicrotic notch) represents

aortic / pulmonic valve closure

28

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

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.

29

why do ventricular volumes remain constant in phase 5?

because all valves are closed

30

End-Systolic volume (ESV)

the residual volume of blood that remains in the ventricle.

31

what is the ESV in the LV?

50ml

32

stroke volume

the difference between end diastolic volume and end systolic volume.

33

what is the approx stroke volume in the ventricle

70ml

34

phase 6

rapid ventricular filling. diastole

35

which valves are open in phase 6

AV valves

36

which valves are closed in phase 6

aortic and pulmonic

37

what contributes to rapid, passive filling of the ventricles?

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

38

what does the v-wave represent

peak of the atrial pressure just before the AV valve opens

39

what is y descent

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

40

what sounds do AV valves make as they open

none

41

s3

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

42

phase 7

reduced ventricular filling (diastole)

43

phase 7 which valves are open

AV valves

44

phase 7 which valves are closed

aortic and pulmonic

45

during what phase is ventricular filling nearing completion

7

46

as the ventricles fill with blood they become

less compliant (stiff) and pressures rise

47

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

less ventricular filling

48

what phases are part of ventricular systole

2 3 4

49

what phases are part of ventricular diastole

1 5 6 7

50

what causes heart sounds

closing of valves

51

what causes the first heart sound

closure of AV valves

52

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

phase 3 rapid ejection

53

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

6 rapid ventricular filling

54

how much does atrial kick usually contribute to ventricular filling

10%

55

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

up to 40%of ventricular filling

56

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

it is lost, leading to inadequate filling.