Mechanical properties of the heart, starlings’ law:

Question 1

Elements of contraction: What are the element of contraction

Answer 1

• CC (contractile elements)
• SEC (serial elastic component)
• PEC (parallel elastic component)
• Col (collagen fiber system)
• Isometric phase
• Isotonic phase
• The collagen fibers

Question 2

Elements of contraction: CC name and example

Answer 2

contractile component: Actin and myosin

Question 3

Elements of contraction: SEC name

Answer 3

serial elastic component:

Question 4

Elements of contraction: SEC explain

Answer 4

serial elastic component: Attached to CC, relaxes during diastole and is expanded during systole.

Question 5

Elements of contraction: PEC name

Answer 5

parallel elastic component

Question 6

Elements of contraction: PEC explain

Answer 6

parallel elastic component: Attached to CC and to the SEC. Stretched by the blood filling heart during diastole

Question 7

Elements of contraction: Col name

Answer 7

collagen fiber system:

Question 8

Elements of contraction: Col explain

Answer 8

collagen fiber system: Overexpansion and rupture of the tissue is prevented by the rich collagen fiber system.

Question 9

Elements of contraction: Isometric phase explain

Answer 9

At the beginning of the contraction the weight stretches the SEC elements only.

Question 10

Elements of contraction: Isotonic phase:

Answer 10

When the stretch in the SEC gets into balance with the weight, the weight begins to move.

Question 11

Collagen fibre explain

Answer 11

collagen fibers are
expanded and display maximal resistance to prevent rupture.

Question 12

When do low performances occur in single working fibre

Answer 12

at short sarcomeric lengths which then
increases when the sarcomeric length is increased

Question 13

Optimal position for both heart and skeletal muscle in single working fibre

Answer 13

1,9-2,5 micrometer sarcomeric lengths.

Question 14

Entry of Calcium to sarcomeric space …..
( in single working fibre)

Answer 14

The entry of the calcium into the sarcomeric space is length dependent in the heart muscle.

Question 15

Properties of the total working musculature: What is the law of the heart by Starling and Frank

Answer 15

The heart muscle can adapt itself to higher requirements automatically, without the intervention of the nervous system.

Question 16

Properties of the total working musculature: Volume fraction ( total working musculature)

Answer 16

During contraction and relaxation the heart empties a part of its blood content towards the circulatory bed and then takes up blood from the periphery. The emptying is not complete: the remaining fraction is of big importance in the adaption.

Question 17

Properties of the total working musculature:
The amount of blood found in the heart by the end of diastole is called

Answer 17

end diastolic volume (EDV)

Question 18

Properties of the total working musculature: end diastolic volume (EDV)

Answer 18

The amount of blood found in the heart by the end of diastole is called

Question 19

Properties of the total working musculature: The amount of blood remaining in the heart by the end of systole is called

Answer 19

end systolic volume (ESV)

Question 20

Properties of the total working musculature: end systolic volume (ESV)

Answer 20

The amount of blood remaining in the heart by the end of systole is called

Question 21

Properties of the total working musculature: The difference between ESV and EDV is called

Answer 21

stroke volume (SV), this volume fraction passes into the aorta at each cycle.

Question 22

Properties of the total working musculature: What is cardiac output

Answer 22

Cardiac output = volume of blood forwarded by the left ventricle into the aorta per unit time.

Question 23

Properties of the total working musculature: Cardiac output equation:

Answer 23

CO = SV (stroke volume) x FR (frequency)

Question 24

Properties of the total working musculature: SV=

Answer 24

SV=EDV-ESV

Question 25

Properties of the total working musculature: Measuring cardiac output:

Answer 25

Cardiac output is equal to the total oxygen consumption divided by the arterio-venous oxygen concentration difference.

Question 26

Properties of the total working musculature: what does the Fick’s principle measure

Answer 26

Measuring cardiac output

Question 27

Starlings experiment: what is it and what did it prove?

Answer 27

First he increased the venous return, then he changed the peripheral resistance. Proved that the heart can adapt to the increased load.

Question 28

Starlings experiment: what does it explain

Answer 28

By increased venous return= the cardiac output and stroke volume increased. By changing the peripheral resistance= the stroke volume and cardiac output stay the same (because EDV and ESV increases proportionally)

Question 29

Starlings experiment: Physiological importance

Answer 29

The heart can increase its diastolic reserves so that it can perform better:

Question 30

the work of the heart: The total work of the heart is composed

Answer 30

The total work of the heart is composed of outer work (mechanical work) and inner work (heat production):

Question 31

the work of the heart: The total work of the heart equation

Answer 31

Wt= Wo + Wi

Question 32

the work of the heart: outer work of the heart equation word

Answer 32

the product of the stroke volume times the pressure difference between the aorta and the vena cava (∆P)

Question 33

the work of the heart: outer work of the heart equation letter

Answer 33

Wo = SV x ∆P

Question 34

the work of the heart: how does the heart gain its energy

Answer 34

heart gains its energy purely from the oxidative processes

Question 35

the work of the heart: the total work of the heart can be determined by equation word

Answer 35

measuring the total oxygen consumption of the tissue

Question 36

the work of the heart: the total work of the heart can be determined by equation letter

Answer 36

Wt = oxygen consumption x energy equivalent of O2.

Question 37

the work of the heart: How to calculate the efficiency of the heart

Answer 37

Knowing Wo and Wt the efficiency (E) of the heart can also be calculated: E = Wo/Wt

Question 38

Rushmer diagram: what is it?

Answer 38

Analyses the work of the heart in the pressure-volume coordinate system.

Question 39

Rushmer diagram: 1

Answer 39

Mitral valve close, isovolumetric contraction

Question 40

Rushmer diagram: 2

Answer 40

Aortic valves open, ejection phase

Question 41

Rushmer diagram: 3

Answer 41

Semilunar valves close, isovolumetric relaxation

Question 42

Rushmer diagram: 4

Answer 42

Mitral valves open, filling.

Question 43

Performance of the heart: equation words

Answer 43

Performance = work/time

Question 44

Performance of the heart: equation letter

Answer 44

W/t = PxV/t

Question 45

Performance of the heart: equation explain

Answer 45

Since the heart maintains a close to constant peripheral pressure (constant P), the performance (W/t) is mainly determined by the volume flow.