Lecture 11: Events of The Cardiac Cycle (Hayward) Flashcards Preview

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Flashcards in Lecture 11: Events of The Cardiac Cycle (Hayward) Deck (27):
1

For ECGs-Lead III involves putting your +/- electrodes on:

LA-, LL+

2

An increase in extracellular Na+ --> intracellular Ca conc.?

reduce

3

cardiac cycle

the repeating cycle of contraction (systole) and relaxation (diastole) which pumps blood through the circulatory system unidirectionally

4

Which valves are open/closed during diastole?

AV valves open, semilunar valves closed

5

systole is initiated by:

SA node discharge

6

duration of volume injection phase of systole is driven by duration of

AP (volume injection will occur when AP is in plateaue phase and will decrease once repolarization occurs)

7

when do ventricles fill?

during diastole

8

2 phases of systole

isovolumic, volume injection

9

isovolumic phase of systole

ventricles begin to contract, pressure in ventricles is greater than P in atria, but lower than P out in vessels

10

volume injection phase of systole

valves open because pressure in ventricles becomes greater than P in outside vessels

11

AV valves open during:

diastole and atrial contraction

12

5 main phases of cardiac cycle

1) ventricular filling (diastole)
2) atrial contraction (diastole)
3) isovolumic ventricular contraction (systole)
4) ventricular ejection (systole)
5) isovolumic ventricular relaxation (diastole)

13

phase 1: ventricular filling (diastole) + ECG

AV valves open, ventricles filling. Semilunar valves closed. Flat line/beginning of P in ECG

14

phase 2: atrial contraction (diastole) + ECG

SA node fires, atria contract, P in atria higher than it was previously. Ventricles still filling. Semilunar valves still closed. End of P, Q+R waves on ECG

15

phase 3: isovolumic ventricular contraction (systole) + ECG

AV valves close as P in Ventricles> P in Atria. Semilunar valves still closed. S wave

16

phase 4: ventricular ejection (systole) + ECG

Semilunar valves open, volume ejection from ventricles to vessels. ST, beginning of T on ECG

17

phase 5: isovolumic ventricular relaxation (diastole) + ECG

Semilunar valves close as P in ventricles drops and ventricles relax.

18

Interval between systolic periods of the cardiac cycle ____ with increased parasym. drive

increases.

19

cardiac cycle length =

HR or RR interval

20

a wave***

atrial pressure assoc. with atrial contraction

21

c wave ***

caused by change in atrial pressure as AV valves close and valve moves slightly back into atrium (pressure wave in atria during ventricular contraction during isovolumic phase)

22

end diastolic volume

volume in ventricle at end of diastole

23

what causes first heart sound?

mitral valve closing

24

dichrotic nothch

pressure wave assoc. with Aortic valve closing

25

Ejection fraction

A measure of contractility. Ratio of blood ejected per beat (stroke volume) to volume of blood in the ventricles at the end of diastole (end-diastolic volume). EF = (EDV-ESV)/EDV

26

What causes 2nd heart sound?

aortic valve closing

27

end-systolic volume

volume in ventricle at end of systole

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