Lecture 11: Events of The Cardiac Cycle (Hayward)

Question 1

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

Answer 1

LA-, LL+

Question 2

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

Answer 2

reduce

Question 3

cardiac cycle

Answer 3

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

Question 4

Which valves are open/closed during diastole?

Answer 4

AV valves open, semilunar valves closed

Question 5

systole is initiated by:

Answer 5

SA node discharge

Question 6

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

Answer 6

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

Question 7

when do ventricles fill?

Answer 7

during diastole

Question 8

2 phases of systole

Answer 8

isovolumic, volume injection

Question 9

isovolumic phase of systole

Answer 9

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

Question 10

volume injection phase of systole

Answer 10

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

Question 11

AV valves open during:

Answer 11

diastole and atrial contraction

Question 12

5 main phases of cardiac cycle

Answer 12

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

Question 13

phase 1: ventricular filling (diastole) + ECG

Answer 13

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

Question 14

phase 2: atrial contraction (diastole) + ECG

Answer 14

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

Question 15

phase 3: isovolumic ventricular contraction (systole) + ECG

Answer 15

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

Question 16

phase 4: ventricular ejection (systole) + ECG

Answer 16

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

Question 17

phase 5: isovolumic ventricular relaxation (diastole) + ECG

Answer 17

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

Question 18

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

Answer 18

increases.

Question 19

cardiac cycle length =

Answer 19

HR or RR interval

Question 20

a wave***

Answer 20

atrial pressure assoc. with atrial contraction

Question 21

c wave ***

Answer 21

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)

Question 22

end diastolic volume

Answer 22

volume in ventricle at end of diastole

Question 23

what causes first heart sound?

Answer 23

mitral valve closing

Question 24

dichrotic nothch

Answer 24

pressure wave assoc. with Aortic valve closing

Question 25

Ejection fraction

Answer 25

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

Question 26

What causes 2nd heart sound?

Answer 26

aortic valve closing

Question 27

end-systolic volume

Answer 27

volume in ventricle at end of systole