Cardiac Cycle

Question 1

What are the basic 3 events in the cardiac cycle

Answer 1

LV contraction

LV relaxation

LV filling

Question 2

What parts of the cardiac cycle are in left ventricle contraction

Answer 2

Isovolumetric contraction

Maximal elejection

Question 3

What parts of the cardiac cycle are in left ventricle relaxation

Answer 3

Start of relaxation and reduced ejection

Isovolumetric relaxation

Rapid LV filling and LV suction

Slow LV filling (diastasis)

Atrial booster

Question 4

What is ventricular contraction

Answer 4

Systole

Question 5

What happens at systole

Answer 5

Wave of depolarisation arrives

Opens the L-calcium tubule

Ca2+ arrive at contractile proteins

LVp rises > LAp

MV closes

LVp rises (isovolumetric contraction) > Aop

AoV opens and ejection starts

Question 6

In systole is the L ventricle or atria have more pressure

Answer 6

Left ventricle pressure

Question 7

In isovolumetric contraction does the L ventricle or atria have more pressure

Answer 7

Left ventricle pressure

Question 8

What valve opens in systole to start ejection

Answer 8

Aortic valve

Question 9

What is diastole

Answer 9

Ventricular relaxation

Question 10

Describe diastole

Answer 10

LVp peaks then decreases

Influence of phosphorylated phospholambdam cytosolic calcium is taken up into the SR

Phase of reduced ejection

Ao flow is maintained by aortic distensibility

LVp < AoP

Ao. valve closes

Isovolumetric relaxation the MV opens

Question 11

In diastole is the left ventricle pressure more than the aortic pressure

Answer 11

Less than

Question 12

Describe ventricular filling

Answer 12

LVp < LAp

MV opens

Rapid filling starts

Ventricular suction contributes

Diastasis (seperation) LVp = LAp filling temporarily stops

Filling is renewed when A contraction raises LAp creating pressure gradient

Question 13

In ventricular filling is the left ventricle or atria have more pressure

Answer 13

Atria

Question 14

What does ventricular suction contribute to

Answer 14

Ventricular filling

Question 15

What is physiologic systole

Answer 15

Isovolumetric contraction

Maximal ejection

Question 16

What is cardiologic systole

Answer 16

From M1 to A2

Only part of isovolumetric contraction - includes maximal and reduced ejection phases

Question 17

What is physiologic diastole

Answer 17

Reduced ejection

Isovolumetric relaxation

Filling phases

Question 18

What is cardiologic diastole

Answer 18

A2 to M11 interval - filling phases included

Question 19

Define preload

Answer 19

Load present before LV contraction has started

Question 20

Define afterload

Answer 20

Load after the ventricle starts to contract

Question 21

Define starlings Law

Answer 21

Within physiologic limits, the larger the volume off the heart, the greater energy of its contraction and the amount of chemical change at each contraction

Question 22

In starlings law what is LV filling pressure

Answer 22

Left atrium pressure - left ventricle diastolic pressure

Question 23

In the cardiac sarcomere at 80% of the optimal length, what % of the maximal force is produced

Answer 23

10%

Question 24

What is the maximal length of the cardiac sarcomere

Answer 24

2.2 um

Question 25

When the sarcomere lengthens to 85% of Lmax what is effected

Answer 25

Physiologic LV volume

Question 26

What is the relationship of the sarcomere

Answer 26

Length-dependent activation All or none

Question 27

Define contractility (inotropic state)

Answer 27

State of the heart which enables it to increase its contraction velocity, to achieve higher pressure, when contractility is increased independent of load

Question 28

Define elasticity

Answer 28

Myocardial ability to recover its normal shape after removal of systolic stress

Question 29

Define compliance

Answer 29

Relationship between the change in stress and resultant strain (dP/dV)

Question 30

Define diastolic distensibility

Answer 30

Pressure required to fill the ventricle to the same diastolic volume

Question 31

Define myocardial work

Answer 31

Pressure-volume loop reflects contractility in the end-systolic pressure volume relationship, while compliance is reflected at the end diastolic pressure volume relastionship

Question 32

When is compliance reflected

Answer 32

End diastolic pressure volume relationship

Question 33

When is contractility reflected

Answer 33

End-systolic pressure volume relationship

Question 34

What type of contraction does the heart perform

Answer 34

Isometric conditions found during isovolumetric contraction (isotonic are impossible)

Question 35

What does sympathetic stimulation do

Answer 35

Increases HR (positive chronotropic) Increases force of contraction (positively inotropic) Increases CO

Question 36

What does parasympathetic stimulation do

Answer 36

Decreases HR (negatively chronotropic) Decreases force of contraction (negatively inotropic) Increases CO

Question 37

What is sympathetic stimulation controlled by

Answer 37

Adrenaline and noradrenaline + type 1 beta adrenoreceptors Increased adenylyl cyclase = increase cAMP

Question 38

What does increased sympathetic stimulation do

Answer 38

Increases HR (up to 180-250bmp) Increases force of contraction Large increase in CO (by up to 200%)

Question 39

What does decreased sympathetic stimulation do

Answer 39

Decreases HR and force of contraction Decreases CO (by up to 30%)

Question 40

What is parasympathetic stimulation controlled by

Answer 40

Acetylcholine M2 receptors - inhibit adenyl cyclase = reduced cAMP

Question 41

What does increased parasympathetic stimulation lead to

Answer 41

Decreased HR (temporary pause or as low as 30-40bpm) Decreased force of contraction Decreased CO (by up to 50%)

Question 42

What does decreased parasympathetic stimulation do

Answer 42

Increased HR

Question 43

What is the pressure in the right atrium

Answer 43

0-4mmHg

Question 44

What is the pressure in the right ventricle during systole

Answer 44

25mmHg

Question 45

What is the pressure in the right ventricle during diastole

Answer 45

4mmHg

Question 46

What is the pressure in the pulmonary artery during systole

Answer 46

25mmHg

Question 47

What is the pressure in the pulmonary artery during diastole

Answer 47

10mmHg

Question 48

What is the pressure in the left atrium

Answer 48

8-10mmHg

Question 49

What is the pressure in the left ventricle during systole

Answer 49

120mmHg

Question 50

What is the pressure in the right ventricle during diastole

Answer 50

10mmHg

Question 51

What is the pressure in the aorta during systole

Answer 51

120mmHg

Question 52

What is the pressure in the aorta during diastole

Answer 52

80mmHg

Question 53

Describe the filling phase

Answer 53

Ventricles fill with blood during diastole and atrial systole

Question 54

Describe outflow phase

Answer 54

Ventricles continue to contract, pushing blood into the aorta and pulmonary trunk (systole)

Question 55

Describe isovolumetric relaxation

Answer 55

Ventricles relax, ready to re-fill with blood in the next filling phase

Question 56

Describe what happens in the filling phase

Answer 56

Ventricle pressure is higher than the atria causing the atrioventricular valves (mitral/tricuspid) valves to close

Question 57

How long does isovolumetric contraction last

Answer 57

50ms - while pressure builds up

Question 58

At the beginning of diastole what valves are open

Answer 58

Atrioventricular valves an

Question 59

What happens during diastole

Answer 59

Tricuspid and mitral valves are open Contraction of atrium moves blood into the ventricle (Can move straight through) Tricuspid/mitral valve prevents blood from flowing back

Question 60

Describe diastole

Answer 60

Ventricles filled with blood Atrioventricular valves close Semilunar valves open Contraction of ventricles