Smooth Muscle Study Questions Bank

11 Questions | By Chachelly | Last updated: Mar 22, 2022 | Total Attempts: 3179

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Smooth Muscle Study Questions Bank - Quiz

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1.

Smooth muscle cells are initiated to contract by all of the following ways except which?
- A.
  
  Depolarization from a neighboring cell spread through connexon channels
- B.
  
  Norepinephrine binding to α1-adrenergic receptors
- C.
  
  Acetylcholine binding to nicotinic acetylcholine receptors
- D.
  
  The movement of a bolus of food through the small intestine
2.

Which of the following muscle proteins plays a critical role in contraction of both smooth and striated muscle?
- A.
  
  Calmodulin
- B.
  
  Troponin
- C.
  
  Tropomyosin
- D.
  
  Actin
- E.
  
  Myosin light chains
3.

During the process of excitation-contraction coupling in smooth muscle, intracellular [Ca²⁺] is increased through all of the following methods except which?
- A.
  
  Ca2+ influx from extracellular stores through voltage-activated Ca2+ channels
- B.
  
  Ca2+ influx from the sarcoplasmic reticulum through IP3 receptors
- C.
  
  Ca2+ influx from extracellular stores through ryanodine receptors
- D.
  
  Ca2+ influx from extracellular stores through ligand-gated Ca2+ channels
4.

Which of the following temporal sequences is correct for excitation-contraction coupling in smooth muscle?
- A.
  
  Ca2+ influx through IP3 receptors, cross-bridge cycling, Ca-calmodulin activation of MLCK, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger
- B.
  
  Ca2+ influx through RyR in the SR, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger, Ca-calmodulin activation of MLCK, cross-bridge cycling
- C.
  
  Ca2+ influx through L-type Ca2+ channels, Ca2+ activated Ca2+ release from RyR in the SR, Ca-calmodulin activation of MLCK, cross-bridge cycling, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger
- D.
  
  Ca2+ influx through store-operated Ca2+ sensitive channels, cross-bridge cycling, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger, Ca-calmodulin activation of MLCK
5.

When comparing the contractile responses in smooth and skeletal muscle, which of the following is most different?
- A.
  
  The source of activator calcium
- B.
  
  The role of calcium in initiating contraction
- C.
  
  The mechanism of force generation
- D.
  
  The source of energy used during contraction
- E.
  
  The nature of the contractile proteins
6.

In excitation-contraction of smooth muscle, calcium binds to what protein after influx into the cytoplasm?
- A.
  
  Calmodulin
- B.
  
  Myosin light chains
- C.
  
  Troponin
- D.
  
  Tropomyosin
- E.
  
  Protein kinase A
7.

Which of the following enzymes is responsible for dephosphorylating myosin light chains, thereby causing smooth muscle relaxation?
- A.
  
  Calmodulin
- B.
  
  Protein kinase A
- C.
  
  Myosin light chain kinase
- D.
  
  Myosin light chain phosphatase
- E.
  
  Phospholipase C
- F.
  
  Actomyosin ATPase
8.

The role of myosin light-chain protein in smooth muscle is what?
- A.
  
  Bind to calcium ions to initiate excitation-contraction coupling
- B.
  
  Phosphorylate cross-bridges, thus driving them to bind with the thin filament
- C.
  
  Split ATP to provide the energy for the power stroke of the cross-bridge cycle
- D.
  
  Dephosphorylate myosin light-chains of the cross-bridge, thus relaxing the muscle
- E.
  
  Pump calcium from the cytosol back into the sarcoplasmic reticulum
9.

Single-unit smooth muscle differs from multiunit smooth muscles how?
- A.
  
  Single-unit muscle contraction speed is slow, while multiunit is fast
- B.
  
  Single-unit muscle has T-tubules, while multiunit does not
- C.
  
  Single-unit muscles are not innervated by autonomic nerves
- D.
  
  Single-unit muscle produces action potentials spontaneously that spreads to neighboring cells, while multiunit does not
10.

Which of the following enzymes is responsible for phosphorylating myosin light chains in order to activate smooth muscle contraction?
- A.
  
  Calmodulin
- B.
  
  Protein kinase A
- C.
  
  Myosin light chain kinase
- D.
  
  Phospholipase C
- E.
  
  Actomyosin ATPase
11.

Which characteristic or component is shared by skeletal muscle and smooth muscle?
- A.
  
  Thick and thin filaments arranged in sarcomeres
- B.
  
  Troponin
- C.
  
  Elevation of intracellular [Ca2+] for excitation-contraction coupling
- D.
  
  Spontaneous depolarization of the membrane potential
- E.
  
  High degree of electrical coupling between cells