Cardiac Muscle Mechanics

Question 1

SV can increase put to abut

Answer 1

50%

Question 2

HR can increase to a max. Of approx. _____ your age

Answer 2

220

Question 3

Increases in _____ alone decreases the duration of diastole

Answer 3

Heart rate

Question 4

Decreasing the duration of diastole decreases the

Answer 4

Ventricular filling and thus could decrease SV

Question 5

SV increases or decreases during exercise

Answer 5

Increases

Question 6

SV= EDV - ESV

What are the factors that regulate SV?

Answer 6

EDV- preload

ESV- afterload and inotropy

Question 7

Wall stretch is max. At the

Answer 7

End of diastolic vol. (EDV) or end diastolic pressure (EDP)

Question 8

Increases in either EDV or EDP _________ the sarcomeres and increases the

Answer 8

EDP stretches the sarcomeres and thus increases the force of the next contraction

Question 9

Preload (2) meaning

Answer 9

1. Initial stretching of the cardiac myocytes prior to contraction
2. Average ventricular sarcomeres length at the end of diastole

Question 10

Length tension curve shows that

Answer 10

Increasing the length (sarcomeres stretch) results in increasing the contractile force

Question 11

Increases in EDV produced ______ in contractile force

Answer 11

Increases

Question 12

OTTO frank on experiments on intact hearts was the study

Answer 12

Of the effects of diastolic stretch on contraction

Question 13

Increased filling pressure leads to ________ EDV or EDP resulting in

Answer 13

Increase in EDV or EDP resulting in an increased SV at a constant aortic pressure

Question 14

Frank starling law of the heart

Answer 14

The greater the volume of blood entering the heart during diastole the greater the volume of blood ejected during systolic contraction

Question 15

Increased EDP or EDV results from increasing

Answer 15

Venous return to the heart

Question 16

Stretching a resting cardiac fiber causes an immediate rise in

Answer 16

Contractile force in the very next contraction

Question 17

Contractile force is the same as

Answer 17

SV

Question 18

With ____, the sarcomeres length allow for more optimal cross-bridge formation

Answer 18

Stretch

Question 19

True or false:

Too much stretch or too much contraction can lead to poor functioning sarcomeres and thus inefficient contraction force

Answer 19

Yep

Question 20

Stretching the myofibers increases the

Answer 20

Affinity of troop in C for Ca2+

Question 21

At longer sarcomeres length, Ca2+ activates more or less thin filaments at physiological concentrations

Answer 21

More

Question 22

Compliance if the ratio of

Answer 22

Volume change to pressure change

Question 23

All ventricles exhibit increasing stiffness (deceasing compliance) at higher/lower volumes

Answer 23

Higher

Question 24

Ventricular hypetrophy _________ compliance and ________ volume in ventricle at a given EDP leading to a _________ in sarcomeres stretch

Answer 24

Decreased compliance and decrease in volume leading to a decrease in sarcomere stretch

Question 25

Preload affected by compliance changes?

Answer 25

Yep

Question 26

Dilation of ventricle due to chronic volume overload leads to a _______ compliance and allows for a _____ EDV at a lower EDP with stretched sarcomeres

Answer 26

Leads to a increased compliance and allows for a greater EDV

Question 27

Increase in venous return leads to a increase or decrease in EDV (preload)

Answer 27

Increase which leads to increase SV and increased ventricular stroke work

Question 28

True or false:

From beat to beat, the heart can adjust its force of contraction to pump the volume of blood that fills it in the previous diastole

Answer 28

True

Question 29

Heterometric regulations is based on the changes in

Answer 29

Volume

Question 30

Afterload

Answer 30

The load against which the heart must contract to eject the blood

Question 31

For the left ventricle, the major component of the afterload is the ________ and for the right ______

Answer 31

Left is the aortic pressure and the right is the pulmonary arterial pressure

Question 32

Another component of afterload is the

Answer 32

Ventricular wall stress

Question 33

Afterload increases with increasing pressure during systole and ______ with ventricular hypertrophy

Answer 33

Decreases

Question 34

With increasing afterload the velocity

Answer 34

Decreases

Question 35

Increasing aortic pressure represents _____ after load

Answer 35

Increasing

Question 36

Will the increased afterload reduce SV?

Answer 36

Yep, systole occurs in a finite time

Question 37

The heart must develop a higher pressure to open the aortic valve thus the shortening velocity will

Answer 37

Decrease

Question 38

Afterload effects on cardiac performance are not a function of sarcomere length and are termed

Answer 38

Homeometric regulation

Question 39

What might partically compensate for the reduction in SV due to increased afterload?

Answer 39

The venous return will be added to the increased ESV to give an increased preload (EDV)

Question 40

An increase in afterload shifts the Frank-sterling curve _______ and to the _______ thus decreasing SV at any preload

Answer 40

Down and to the right

Question 41

A decreased afterload shifts the F-S curve ___ and to the ____ thus increasing the SV at any preload

Answer 41

Upward and to the left

Question 42

True or false:

Changes in preload alters Vmax

Answer 42

False, no changes

Question 43

Increase in preload increases: (2)

Answer 43

1. Velocity of shortening at a given afterload

2. Max w/out changing V,ax

Question 44

Intrinsic measure of cardiac function independent of extrinsic factors like preload and afterload

Answer 44

Inortropy

Question 45

Inotropic state is increased by

Answer 45

Sympathetic stimulation to the heart and by epinephrine by the adrenal medullary

Question 46

Contractility is decreased by

Answer 46

Parasympathetic stimulation

Question 47

Contractility is related to (2)

Answer 47

1. To the rate of force development during ejection

2. Related to the ESPVR- end systolic pressure volume relationship

Question 48

With increased inotropy there is an ______ force. (SV) at any preload

Answer 48

Increased

Question 49

An increase in inotropy ______ velocity of shortening (SV) at any afterload

Answer 49

Increases

Question 50

Contractility increases Vmax

Answer 50

Yep

Question 51

Positive inotropic effects result from (3)

Answer 51

1. Increased rate of delivery of Ca2+ to the myofibrils
2. Increased binding of Ca2+ to troponin C
3. Increased rate of cross-bridge cycling

Question 52

Inotropic state can be influenced by other factors

Answer 52

Increased heart rate which can increase intracellular Ca2+

Question 53

Loss of inotropy can lead to

Answer 53

Heart failure, cardiomyopathy and ischemia

Question 54

What drugs can be used clinically to increase inotropy?

Answer 54

• digoxin

- B- agonist

Question 55

Because preload affects cardiac function by changing the sarcomere length, this type of regulation is called

Answer 55

Heterometric regulation

Question 56

The ejected volume will change to give the same ESV (2)

Answer 56

1. Increased venous return, the extra blood over and above the normal EDV will be ejected
2. If there is decreased venous return, the volume ejected will be decreased