Chapter 07: Excitation of Skeletal Muscle: Neuromuscular Transmission and Excitation-Contraction Coupling

Chapter 07: Excitation of Skeletal Muscle: Neuromuscular Transmission and Excitation-Contraction Coupling

Complete Chapter Questions With Answers

Sample Questions Are Posted Below

1. A 45-year-old man has botulinum toxin (Botox®) injections in the frontalis muscles. Which of the following sets of changes are most likely to occur in the treated muscles with repeated injections over a period of ten years?

Fiber diameter             Fiber number               Contraction velocity

1. decreased                    decreased                    decreased
2. decreased                    decreased                    increased
3. decreased                    increased                     increased
4. increased                     decreased                    decreased
5. increased                     decreased                    increased
6. increased                     increased                     increased

ANS: A

2. Which of the following represents the correct temporal order of events for skeletal muscle?

First                                         Second                                    Third

1. End plate potential Muscle action potential           Nerve action potential
2. End plate potential Nerve action potential             Muscle action potential
3. Muscle action potential End plate potential                  Nerve action potential
4. Muscle action potential Nerve action potential             End plate potential
5. Nerve action potential End plate potential                  Muscle action potential
6. Nerve action potential Muscle action potential           End plate potential

ANS: E

3. Myasthenia gravis is an autoimmune disease in which antibodies damage which of the following?
4. Acetylcholine
5. Ligand-gated channels on postsynaptic membrane
6. Ligand-gated channels on presynaptic membrane
7. Voltage-gated channels on postsynaptic membrane
8. Voltage-gated channels on presynaptic membrane

ANS: B

4. Lambert-Eaton myasthenic syndrome is an autoimmune disease in which antibodies damage which of the following?

1. Acetylcholine
2. Ligand-gated channels on postsynaptic membrane
3. Ligand-gated channels on presynaptic membrane
4. Voltage-gated channels on postsynaptic membrane
5. Voltage-gated channels on presynaptic membrane

ANS: E

5. A 59-year-old college professor visits his physician because of muscle fatigue that worsens later in the day. The physician notices that the man has droopy eyelids and seems to have an overall weakness in his muscles. After the intravenous administration of Tensilon®, which blocks degradation of acetylcholine, the droopy eyelids and symptoms of muscle weakness appear to subside. Which of the following best describes the patient’s condition?

1. Encephalitis
2. Fibromyalgia
3. Flaccid paralysis
4. Myasthenia gravis
5. Poliomyelitis

ANS: D