IMSPQ P1 - Muscle Physiology Quiz

Each Myofibril in a muscle fiber is surrounded by …

• Epimysium

• Perimysium

• Endomysium

• Sarcoplasmic Reticulum

• Sarcolemma

The thin filament is formed by aggregation of …-protein into a …-protein

• Globular-protein into a filamentous-protein

• Globular-protein into a fibrous-protein

• Myosin-protein into a contractile-protein

• Tropomyosin-protein into a regulatory-protein

• Troponin-protein into a complex-protein

Which characteristic or component is shared by skeletal muscle and smooth muscle?

• Thick and thin filaments

• Troponin

• Elevation of extracellular [Ca2+] for excitation-contraction coupling

• Spontaneous depolarization of the membrane potential

• High degree of electrical coupling between cells

Repeated stimulation of a skeletal muscle fiber causes a sustained contraction (tetanus). Accumulation of which solute in intracellular fluid is responsible for the tetanus?

• Na+

• K+

• Cl-

• Mg2+

• Ca2+

In skeletal muscle, which of the following events occurs before depolarization of the T tubules in the mechanism of excitation-contraction coupling?

• Depolarization of the sarcolemmal membrane

• Opening of Ca2+ release channels on the sarcoplasmic reticulum (SR)

• Uptake of Ca2+ into the SR by Ca2+ - ATPase

• Binding of Ca2+ to troponin C

• Binding of actin and myosin

Which of the following causes rigor in skeletal muscle?

• Lack of action potentials in motoneurons

• An increase in intracellular Ca2+ level

• A decrease in intracellular Ca2+ level

• An increase in ATP level

• A decrease in ATP level

Smooth muscle has T tubule. Does it true?

• True, but only in specialized smooth muscle cells

• False, smooth muscle lacks T tubules but has caveolae instead

• Partially true, smooth muscle has structures functionally similar to T tubules

• True, smooth muscle contains modified T tubules for calcium signaling

• False, smooth muscle relies on caveolae for calcium influx instead of T tubules

Contraction of smooth muscle in response to an agent that does NOT produce a change in membrane potential is termed?

• Pharmacomechanical coupling

• Electromechanical coupling

• Excitation-contraction coupling

• Receptor-mediated coupling

• Mechanochemical coupling

A rise in intracellular [Ca2+] in smooth muscle results in binding Ca2+ ions to the protein calmodulin and then the Ca2+ -calmodulin complex will activate … which is to phosphorylates the regulatory light chain of myosin.

• Ryanodine receptor (RYR)

• cAMP

• MLCK

• MP

• SERCA2

Relaxation of cardiac muscle involves reaccumulation of Ca2+ by the Sacroplasmic Reticulum (SR) via …

• Calcium channel

• Ca2+ - ADPase

• Ca2+ transporter

• 3Na+ - Ca2+ antiporter

• Phospholamban