Michael Jardine
Quiz by , created more than 1 year ago

PHSI3011 02-1 Cardiac excitation-contraction coupling 2 - how to vary contraction of the heart. - Why the heart needs a different EC coupling system - Basic properties of cardiac EC coupling - Skinned fibres, regulatory proteins, and the [Ca]/tension curve - Structural basis for EC coupling - Ca induced Ca release - Source of Ca - Voltage sensitivity of Ca release - Ca sparks and microdomains

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Michael Jardine
Created by Michael Jardine about 7 years ago
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PHSI3011 02-1 Cardiac excitation-contraction coupling 2 - How to vary contraction of the heart

Question 1 of 5

3

Fill the blank space to complete the text.

Unlike Skeletal muscle, cardiac muscle always recruits every cardiac muscle cell for every contraction. Consequently, contraction force can't be changed by recruiting different numbers of cells for each Compound Action Potential.
So... instead, contractile force is varied using .

Explanation

Question 2 of 5

2

How does increased availability of Calcium increase contractility?

Select one of the following:

  • Binding of Ca to troponin causes movement of tropomyosin so it no longer blocks active site on actin.

  • Binding of Ca to tropomyosin causes movement of troponin so it no longer blocks active site on actin.

  • Binding of Ca to troponin causes movement of actin so it no longer blocks active site on tropomyosin.

  • Binding of Ca to tropomyosin causes movement of actin so it no longer blocks active site on troponin.

  • Binding of Ca to actin causes movement of tropomyosin so it no longer blocks active site on troponin.

  • Binding of Ca to actin causes movement of troponin so it no longer blocks active site on tropomyosin.

Explanation

Question 3 of 5

3

Select from the dropdown lists to complete the text.

[Ca] gradients are pretty bloody important, so pumps and exchangers keep them at the "right" levels. These "right" levels are:
Outside the cell = ( 0.1 μM, 1 000 μM, 2 000 μM )
Inside the cell = ( 0.1 μM, 1 000 μM, 2 000 μM )
Inside the SR = ( 0.1 μM, 1 000 μM, 2 000 μM )

Explanation

Question 4 of 5

1

Adrenaline (aka Epinephrine) has an inotropic effect on cardiac contractility.
Through the following pathway:
1 - binds to receptor on ventricular cell surface
2 - activates G-protein
3 - increased cAMP
4 - activated cAMP-dependent kinases
5 - phosphorylates key proteins whose properties change
6 - phosphorylated proteins include
(i) SM [sic.] Ca channel
(ii) SR Ca pump (phospholamban)
7 - [somethingorother] peak Ca (and force) to change timecourse of systole
...does it DECREASE or INCREASE contractility?

Select one of the following:

  • decrease

  • increase

Explanation

Question 5 of 5

1

SPARKS are:

Select one of the following:

  • Spontaneous [brief] opening of one (or a few) Ryanodine Receptors.

  • Spontaneous [prolonged] opening of one (or a few) Ryanodine Receptors.

  • Spontaneous [brief] opening of one (or a few) SR Ca pumps.

  • Spontaneous [prolonged] opening of one (or a few) SR Ca pumps.

Explanation

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