cardiac cycle

Question 1

what valves close and what valves open in atrial systole

Answer 1

• aortic and pulmonary valves close
• mitral and tricuspid valves open

Question 2

what occurs during atrial systole

Answer 2

• contraction of the atria
  
  1. pressure within atria increases
  2. pressure gradient across the AV valves is generated
  3. contraction “tops off” filling

Question 3

atrial contraction accounts for what percentrage of ventricular filling?

Answer 3

atrial contraction accounts for 10% of ventricular filling at rest

• most of the filling occurs before atrial contraction (during rapid and reduced filling)

Question 4

what is the end-diastolic volume

Answer 4

when the volume of blood in the left ventricle is maximal

Question 5

what occurs during isovolumetric contraction

Answer 5

all valves are closed

• initiated by QRS complex
• rise in vetricular pressure caused AV valves to close
• pressure rises without a change in volume

Question 6

what valves close in isovolumetric contraction

Answer 6

AV valves

Question 7

what happens to ventricular pressure during isovolumetric contraction

Answer 7

depolarization leads to rapid increase in LV pressure

Question 8

ventricular ejection consists of what two phases

Answer 8

1. rapid phase
2. reduced phase

Question 9

what valves are open and closed during rapid ejection

Answer 9

• semilunar valves (aortic and pulmonary valves) open
• AV valves remain closed

Question 10

what occurs during rapid ejection

Answer 10

• when intraventricular pressures exceeds pressures within the great vessels, valves open and blood is ejected
• during this phase, maximal outflow velocity of blood is reached
  
  • most of the volume of blood is ejected
  • dramatic decrease in ventricular volume

Question 11

when is maximal left ventricular systolic (and RV systolic) pressure achieved

Answer 11

rapid ejection

Question 12

what is occuring in the atria as rapid ejection occurs

Answer 12

atrial filling begins, causing atrial pressure to rise

Question 13

end of the rapid ejection phase coincides with what EKG property

Answer 13

with the end of the ST segment

Question 14

what process occurs during reduced ejection

Answer 14

ventricles begin to repolarize, marked by the T wave

Question 15

what valves are opened and closed during reduced ejection

Answer 15

• semilunar valves are open
• AV valves remain closed

Question 16

what happens to ventricular pressure during reduced ejection

Answer 16

ventricular pressure falls because the ventricles are no longer contracting

*volume of blood in ventricles approaches the minumum

Question 17

what is isovolumetric relaxation

Answer 17

• ventricles are fully repolarized
• All valves are closed

Question 18

what causes the aortic and pulmonic valves to close during isovolumetric relaxation

Answer 18

left ventricular pressure declines dramatically, below that of vessel pressure, which causes the valves to close

Question 19

what is the end-systolic volume

Answer 19

volume of blood in a ventricle at the end of contraction, or systole, and the beginning of filling, or diastole.

• ESV is the lowest volume of blood in the ventricle at any point in the cardiac cycle.

Question 20

what occurs during rapid ventricular filling

Answer 20

• ventricular pressures fall below atrial pressures
• AV valves open and LV filling begins

Question 21

what vavles are opened and closed during rapid ventricular filling

Answer 21

• AV valves are open
• SL valves are closed

Question 22

what is the pressure in the left ventricle during rapid ventricular filling

Answer 22

LV pressure is low because the ventricle is relaxed

Question 23

what is the reduced ventricular filling stage (diastasis)

Answer 23

final portion of passive ventricular filling

Question 24

what is the longest phase of the cardiac cycle

Answer 24

reduced ventricular filling

Question 25

during reduced ventricular filling, as ventricles continue to fill with blood, what happens to the pressure gradient across the AV valves

Answer 25

pressure gradient across the AV valves declines because the pressure in the ventricles begins to rise

Question 26

what is the stroke volume

Answer 26

volume of blood ejected on one ventricular contraction * difference between the volume of blood in the ventricle at end of atrial systole (EDV) and following reduced ejection (ESV)

Question 27

how does stroke volume relate to end diastolic volume and end systolic volume

Answer 27

SV = EDV - ESV

Question 28

what information does ejection fraction give us

Answer 28

effectiveness of ventricles in ejecting blood

Question 29

what is ejection fraction? give equation

Answer 29

fraction of EDV that is ejected in one Stroke volume EF = SV/EDV x 100%

Question 30

what is cardiac output?

Answer 30

total volume of blood ejected per unit time

Question 31

how does cardiac output relate to heart rate and stroke volume

Answer 31

CO = HR x SV

Question 32

what is a stenotic valve

Answer 32

* stiff narrow valve * does not open completely * turbulence is created when blood must be forced through

Question 33

what is an insufficient (regurgitation) valve

Answer 33

* valve can not close completely * blood flows backward and collides with incoming blood

Question 34

in aortic stenosis, what happens to left ventricular pressure? what happens to aortic pressure?

Answer 34

* left ventricular pressure is much greater than aortic pressure during ejection * aortic pressure rise is slightly reduced

Question 35

mitral valve stenosis leads to what pressure changes in left atria and left ventricle during filling

Answer 35

* resistance causes blood to back up reducing LV filling * left atrial pressure is greater than left ventricular pressure during filling \*atrium must contract more, increasing left atrial pressure

Question 36

what is aortic regurgitation

Answer 36

leaflets do not provide seal; blood regurgitates back into the LV

Question 37

what happens to left ventricular volume in aortic regurgitation

Answer 37

increase in volume and pressure in LV chamber

Question 38

how does the left ventricle try to compensate for aortic regurgitation

Answer 38

increasing Stroke volume

Question 39

in aortic regurgitation, the increase in LVP causes what to atrial pressure

Answer 39

causes an increase in atrial pressure

Question 40

what is mitral regurgitation

Answer 40

blood regurgitates from LV into left atrium during systole

Question 41

what happens to left atrial pressure in mitral regurgitation

Answer 41

increases \* causes enlargement of the atrial chamber

Question 42

what happens to left ventricular stroke volume during mitral regurgitation

Answer 42

decreases