Hall: Guyton and Hall Textbook of Medical Physiology, 12th Edition
Chapter 08: Excitation and Contraction of Smooth Muscle
Test Bank
1. The contraction of smooth muscle can be attenuated even when intracellular calcium
levels are high. This unique ability of smooth muscle can be attributed to variations in the
activity of which of the following?
A. Actin
B. Adenosine triphosphate (ATP)
C. Calcium-calmodulin complex
D. Calmodulin
E. Myosin light chain phosphatase
2. Multiple elements can regulate the contraction of smooth muscle, including endocrine,
neurocrine, and paracrine factors. This level of diversity in the control of smooth muscle
contraction can be attributed to a diversity of which of the following?
A. Actin-myosin arrangement
B. Calcium sensitivities
C. Cell-surface receptors
D. Motor end plates
E. Subneural cleft architecture
3. The effect of autonomic nerve stimulation on smooth muscle contractile behavior
depends on the types of receptors on the smooth muscle fibers. Which of the following
best describes the effects of acetylcholine and norepinephrine on various types of smooth
muscle?
Acetylcholine Norepinephrine
A. Contraction only Relaxation or contraction
B. Contraction only Relaxation only
C. Relaxation only Contraction only
D. Relaxation only Relaxation only
E. Relaxation or contraction Contraction only
F. Relaxation or contraction Relaxation or contraction
4. Unlike skeletal muscle, the contraction of smooth muscle requires which of the
following?
A. Activation of ryanodine receptors
B. Phosphorylation of myosin light chains
Test Bank
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C. The presence of intracellular calcium
D. Troponin binding of calcium
E. Voltage activation of dihydropyridine receptors
5. Which of the following factors are important for initiating smooth muscle contractions?
Hormones Paracrine factors Autonomic nervous system
A. No No No
B. No No Yes
C. Yes No Yes
D. Yes Yes No
E. Yes Yes Yes
6. The sensitivity of the smooth muscle contractile apparatus to calcium can increase. This
increase in calcium sensitivity can be attributed to a decrease in the levels of which of the
following substances?
A. Actin
B. Adenosine triphosphate (ATP)
C. Calcium-calmodulin complex
D. Calmodulin
E. Myosin light chain phosphatase
7. Which of the following is the correct temporal order of events for the smooth muscle?
A. Myosin light chain (MLC) dephosphorylation, contraction, relaxation, MLC
phosphorylation
B. MLC dephosphorylation, contraction, MLC phosphorylation, relaxation
C. MLC dephosphorylation, relaxation, MLC phosphorylation, relaxation
D. MLC phosphorylation, contraction, MLC dephosphorylation, relaxation
E. MLC phosphorylation, contraction, relaxation, MLC dephosphorylation
F. MLC phosphorylation, MLC dephosphorylation, contraction, relaxation