It is established by the Na\textsuperscript{+}/K\textsuperscript{+} pump, which moves Na\textsuperscript{+} out and K\textsuperscript{+} in.

Question 1

Which of the following statements best describes the difference between skeletal and cardiac muscle cells?

Accepted Answer

Skeletal muscle cells are multinucleated and voluntary, while cardiac muscle cells are single-nucleated and involuntary.

Question 2

Which property of muscle cells allows them to return to their original length after being stretched?

Accepted Answer

Elasticity

Question 3

During the sliding-filament mechanism of contraction, which band remains unchanged as the sarcomere shortens?

Accepted Answer

A band

Question 4

What is the main function of the sarcoplasmic reticulum (SR) in skeletal muscle fibers?

Accepted Answer

Storing and releasing calcium ions

Question 5

Which of the following best describes the role of creatine phosphate in muscle contraction?

Accepted Answer

It immediately regenerates ATP for about 10 seconds of maximum muscle activity.

Question 6

A patient is experiencing muscle fatigue after intense exercise. Which energy source is most likely depleted first?

Accepted Answer

Creatine phosphate

Question 7

Which of the following is TRUE regarding the resting membrane potential of a skeletal muscle fiber?

Accepted Answer

It is established by the Na	extsuperscript{+}/K	extsuperscript{+} pump, which moves Na	extsuperscript{+} out and K	extsuperscript{+} in.

Question 8

Which of the following events occurs FIRST during excitation-contraction coupling in skeletal muscle?

Accepted Answer

Action potential propagates down the T-tubules.

Question 9

Which equation correctly represents the hydrolysis of ATP during the power stroke of muscle contraction?

Accepted Answer

$$\mathrm{ATP} \rightarrow \mathrm{ADP} + \mathrm{P}_i$$

Question 10

A toxin blocks voltage-gated Na	extsuperscript{+} channels in the sarcolemma. What is the most immediate effect on muscle contraction?

Accepted Answer

Action potentials cannot be generated, preventing contraction.

Question 11

Which of the following best describes the function of the neuromuscular junction (NMJ)?

Accepted Answer

It is the site where a motor neuron communicates with a muscle fiber.

Question 12

Which of the following is a regulatory protein that binds calcium and initiates muscle contraction?

Accepted Answer

Troponin

Question 13

During muscle relaxation, which process returns calcium ions to the sarcoplasmic reticulum?

Accepted Answer

Active transport via calcium pumps

Question 14

Which of the following correctly matches the myofilament with its main protein component?

Accepted Answer

Thick filament: myosin

Question 15

A patient with a genetic defect in tropomyosin would most likely experience which of the following?

Accepted Answer

Impaired regulation of actin-myosin binding, leading to abnormal muscle contractions

Question 16

Which of the following best explains why oxidative catabolism is the predominant energy source after one minute of sustained muscle activity?

Accepted Answer

It requires oxygen and produces more ATP per molecule of glucose.

Question 17

Which of the following is TRUE about the end-plate potential at the neuromuscular junction?

Accepted Answer

It is a local depolarization of the muscle fiber membrane caused by Na	extsuperscript{+} influx.

Question 18

Which of the following best describes the role of acetylcholinesterase at the neuromuscular junction?

Accepted Answer

It degrades acetylcholine in the synaptic cleft, terminating the signal.

Question 19

Which of the following is the correct sequence of events in the crossbridge cycle?

Accepted Answer

Myosin binds to actin, power stroke occurs, ATP binds to myosin, myosin detaches from actin.

Muscle Tissue: Structure, Function, and Physiology

Study Guide - Practice Questions