cardiovascular system - cardiac cycle

Question 1

1) atrial contraction

Answer 1

-atrioventricular (AV) valves OPEN
-semilunar (SL) valves CLOSED

Question 2

2) isovolumetric contraction

Answer 2

-(iso = same, so vol. stays same)
-all valves CLOSED
-heart sound S1 audible
-ventricular pressure rises rapidly w/o vol. change

Question 3

3) rapid ejection

Answer 3

-pressure sufficiently high to open SL valves (AV valves closed)
-blood flows rapidly from ventricles to arteries (blood released from heart, heart emptying)
-pressure continues to develop in order to pump blood out (vol. decreases
-120ml start, 50ml left, so stroke vol. = 70ml

Question 4

left ventricular and diastolic vol. (LVDV)

Answer 4

• ~120ml
  -what the max vol. in the heart is at the end of diastole (end of relaxation period)

Question 5

4) reduced ejection

Answer 5

-ventricle repolarises
-tension on ventricle reduces, so rate of ejection falls
-blood flow lessens as mainly from kinetic energy of blood

Question 6

5) isovolumetric relaxation

Answer 6

-pressure that has been developed now dropping
-all valves CLOSED
-ventricular pressure decreases; rate determined by rate of muscle fibre relaxation
-no change in volume

Question 7

left ventricular and systolic vol. (LDSV)

Answer 7

• ~50 ml

Question 8

6) rapid filling

Answer 8

-pressure outside atria greater than pressure within chamber and in ventricles
-atrioventricular (AV) valves OPEN
-semilunar valves (SL) CLOSED
-blood from atria flows into ventricles
-ventricle completely relaxed

Question 9

7) reduced filling

Answer 9

-AV valves OPEN
-SL valves CLOSED
-ventricles are already considerably relaxed
-at end of this phase, ventricle is ~90% filled

Question 10

stages in SYSTOLE (contraction)

Answer 10

1) atrial contraction
2) isovolumetric contraction
3) rapid ejection
4) reduced ejection

Question 11

stages in DIASTOLE (relaxation)

Answer 11

5) isovolumetric relaxation
6) rapid filling
7) reduced filling