PHSI3011 02-1 Cardiac excitation-contraction coupling 2 - How to vary contraction of the heart

Michael Jardine
Quiz by , created about 2 years 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 2 years ago
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Question 1

Question
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 [blank_start]_____[blank_end].
Answer
  • intracellular [Ca]

Question 2

Question
How does increased availability of Calcium increase contractility?
Answer
  • 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.

Question 3

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

Question 4

Question
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?
Answer
  • decrease
  • increase

Question 5

Question
SPARKS are:
Answer
  • 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.