Frank-Starling Law

Question 1

States that the force of ________ is directly proportional to the initial _______ of the muscle fiber, within the physiological limit.

Answer 1

Frank-Sterling Law;
contraction, length

Question 2

4 mechanisms:

1. With increased ______ or end-diastolic volume (the amount of blood in the _______ during the end of diastole, before the heart ________), the initial length of the _______ increases due to increase in _______ size that stretches the muscle fibers

Answer 2

preload, ventricles, contracts;
muscle fiber, chamber

Question 3

4 mechanisms

1. With increased stretch of muscle fibers, the interaction between ______ and _____ filament increases, which increases the force of _______

Answer 3

thick and thin, contraction

Question 4

4 mechanisms:

2. The stretch of muscle fibers opens the stretch sensitive ______ channel which increases the calcium influx into the ______ cell, thus, the force of contraction increases

Answer 4

calcium, myocardial

Question 5

4 mechanisms:

3. Increase in ______ calcium ions further increases the release of calcium from ____________ by activating the calcium-induced calcium channels present on the membrane of this cell organelle.

Answer 5

intracellular, sarcoplasmic reticulum

Question 6

4 mechanisms:

4. Stretch of ______ enhances the affinity of _______ for calcium increasing the binding of calcium to troponin C, which enhances the force of contraction

Answer 6

myocardium, troponin C

Question 7

Mechanisms by which AP causes myofibrils of muscle to contract

Answer 7

Excitation-Contraction Coupling;

Question 8

Excitation-Contraction Coupling

1. Mainly required for RMP
2. Mainly required for AP
3. Mainly required for pacemaker potential
4. Mainly required for muscle contractility

Answer 8

1. K+
2. Na+, Ca2+
3. K+, Ca2+
4. Concentration of Ca2+

Question 9

Review of Excitation-Contraction Coupling

1. ________ of cardiac muscle triggers _______ that passes through t-tubules
2. During _______ (plateau) of AP, there is increased ______ conductance, causing __________ flow.

Answer 9

1. Depolarization, AP
2. Phase 2, Ca2+, inward Ca2+

Question 10

Review of Excitation-Contraction Coupling

3. Inward Ca2+ flow initiates the release of Ca2+ from ______ such release increase the _________ Ca2+.
4. Ca2+ binds to troponin C and _________ moves out allowing actin and myosin to form _________

Answer 10

3. SR, intracellular
4. Tropomyosin, cross-bridges

Question 11

Review of Excitation-Contraction Coupling

5. Thick and thin filaments of actin and myosin slide past each other, resulting in cardiac muscle cell ________
6. Contraction ends when _________ facilitates the reuptake of Ca2+ in SR reducing intracellular Ca2+

Answer 11

5. Contraction;
6. Ca2+ ATPase

Question 12

Review of Excitation-Contraction Coupling

Note:

Force of contraction of cardiac muscle cells is proportional to the amount of ___________

Answer 12

Ca2+ release

Question 13

Represents performance of ventricles at given preload / afterload.

⬆️ contractility, ⬆️ developed _____ and _______ of contraction

Answer 13

Contractility;
Force and velocity

Question 14

_______ is rich in capillaries, 1 capillary/ 1 cardiac muscle fiber

________ distance between capillary membrane and sarcolemma that favilitates delivery of O2 and nutrients

Answer 14

Myocardium,
Diffusion distance