Q: What is the resting membrane potential (RMP) of a skeletal muscle cell, and which equation best represents the charge difference?

RMP = $$-80\ \text{mV} to$$ $$-90\ \text{mV}$$

Q: Which equation represents the activity of the Na+/K+ pump in maintaining the resting membrane potential?

$$3\ \text{Na}^+\ \text{out},\ 2\ \text{K}^+\ \text{in}$$

Question 1

Which structure in skeletal muscle fibers is responsible for storing and releasing calcium ions during muscle contraction?

Accepted Answer

Sarcoplasmic reticulum

Question 2

During the sliding filament model of contraction, which of the following statements is TRUE regarding the length of the A band?

Accepted Answer

The A band remains the same length during contraction.

Question 3

What is the primary function of the T-tubules in skeletal muscle fibers?

Accepted Answer

Conduct electrical signals deep into the muscle fiber

Question 4

Which protein forms the thick filaments in the sarcomere and has a head that binds to actin and ATP?

Accepted Answer

Myosin

Question 5

In a relaxed muscle, which regulatory protein covers the myosin binding sites on actin?

Accepted Answer

Tropomyosin

Question 6

What is the resting membrane potential (RMP) of a skeletal muscle cell, and which equation best represents the charge difference?

Accepted Answer

RMP = $$-80\ 	ext{mV} to$$ $$-90\ 	ext{mV}$$

Question 7

Which event initiates the release of acetylcholine (ACh) from the axon terminal at the neuromuscular junction?

Accepted Answer

Arrival of an action potential at the axon terminal

Question 8

During depolarization of the muscle cell membrane, which ion moves INTO the cell, causing the membrane potential to become more positive?

Accepted Answer

Sodium ($$Na^+)$$

Question 9

What is the function of acetylcholinesterase (AChE) in the synaptic cleft?

Accepted Answer

Degrades acetylcholine to terminate its effect

Question 10

Which of the following best describes the role of titin in the sarcomere?

Accepted Answer

Anchors thick filaments to the Z disc and provides elasticity

Question 11

A patient presents with muscle weakness due to a defect in the sodium channels of their muscle cell membranes. Which phase of the action potential is most likely impaired?

Accepted Answer

Depolarization

Question 12

Which equation represents the activity of the Na+/K+ pump in maintaining the resting membrane potential?

Accepted Answer

$$3\ 	ext{Na}^+\ 	ext{out},\ 2\ 	ext{K}^+\ 	ext{in}$$

Question 13

Which of the following is NOT a component of the triad in skeletal muscle fibers?

Accepted Answer

Z disc

Question 14

If a muscle fiber is unable to release calcium from the sarcoplasmic reticulum, which step of muscle contraction will be directly affected?

Accepted Answer

Excitation-contraction coupling

Question 15

Which region of the sarcomere contains only actin filaments and no myosin?

Accepted Answer

I band

Question 16

During muscle contraction, what happens to the H zone?

Accepted Answer

It shortens

Question 17

Which of the following best describes the process of action potential propagation in muscle fibers?

Accepted Answer

Depolarization triggers opening of voltage-gated sodium channels in adjacent areas, causing a wave of action potential

Question 18

Which scenario would most likely result in continued muscle contraction in the absence of additional nerve stimulation?

Accepted Answer

Deficiency of acetylcholinesterase in the synaptic cleft

Question 19

A toxin blocks the voltage-gated calcium channels in the axon terminal of a motor neuron. What is the most immediate effect on muscle contraction?

Accepted Answer

Acetylcholine is not released into the synaptic cleft

Question 20

Which of the following is a correct sequence of events for skeletal muscle contraction?

Accepted Answer

Events at neuromuscular junction → Generation & propagation of action potential → Excitation-contraction coupling → Cross bridge cycling

Skeletal Muscle Structure and Physiology: ANP College Study Notes

Study Guide - Practice Questions

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