Question 1

Which of the following best describes the role of the sarcoplasmic reticulum in skeletal muscle contraction?

Accepted Answer

It stores and releases calcium ions ($$\mathrm{Ca$$^{2+}$$}) $$necessary for muscle contraction.

Question 2

A patient is unable to flex their forearm at the elbow after an injury. Which muscle is most likely damaged?

Accepted Answer

Biceps brachii

Question 3

During the contraction phase of a muscle twitch, which of the following occurs?

Accepted Answer

Cross-bridge interactions between actin and myosin increase, generating maximum tension.

Question 4

Which of the following is a correct sequence of events at the neuromuscular junction leading to muscle contraction?

Accepted Answer

Acetylcholine is released → Action potential spreads along sarcolemma → Calcium ions released from SR → Cross-bridge formation

Question 5

Which of the following best explains why fast-twitch muscle fibers fatigue more quickly than slow-twitch fibers?

Accepted Answer

Fast-twitch fibers rely primarily on glycolysis, which produces less ATP and more lactic acid.

Question 6

A muscle is contracting but not changing in length while holding a heavy object steady. What type of contraction is this?

Accepted Answer

Isometric contraction

Question 7

Which of the following statements about the sliding filament theory is correct?

Accepted Answer

Thin filaments slide toward the center of the sarcomere, while thick filaments remain stationary.

Question 8

Which of the following is the correct formula for the breakdown of glucose during glycolysis in muscle cells?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} \rightarrow 2\ \mathrm{C_3H_4O_3} + 2\ \mathrm{ATP}$$

Question 9

Which connective tissue layer surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 10

A patient with a cast on their leg for several weeks experiences muscle atrophy. Which of the following best explains this phenomenon?

Accepted Answer

Lack of regular stimulation by motor neurons causes muscle fibers to become smaller and weaker.

Question 11

Which of the following is a function of the diaphragm muscle?

Accepted Answer

Separates the thoracic and abdominopelvic cavities and is essential for breathing.

Question 12

Which muscle group is primarily responsible for extending the knee joint?

Accepted Answer

Quadriceps femoris

Question 13

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

Accepted Answer

CP donates a phosphate group to ADP to rapidly regenerate ATP during the initial seconds of contraction.

Question 14

Which of the following is a characteristic unique to cardiac muscle tissue?

Accepted Answer

Presence of intercalated discs with gap junctions for rapid communication.

Question 15

A muscle that assists the prime mover in performing its action is called a:

Accepted Answer

Synergist

Question 16

Which of the following best explains why the biceps brachii is considered the prime mover for elbow flexion?

Accepted Answer

It is chiefly responsible for producing the movement of flexion at the elbow.

Question 17

Which of the following is a correct description of the 'origin' of a muscle?

Accepted Answer

The end of the muscle that remains stationary during contraction.

Question 18

Which of the following best describes the effect of aging on skeletal muscle tissue?

Accepted Answer

Muscle fibers become smaller in diameter and less elastic, and the ability to recover from injury decreases.

Question 19

Which of the following is a real-life example of an isometric contraction?

Accepted Answer

Holding a heavy box steady without moving it.

Question 20

Which of the following best explains the difference between white and red muscles?

Accepted Answer

White muscles are dominated by fast fibers and appear pale, while red muscles are dominated by slow fibers and appear reddish due to myoglobin and blood vessels.

The Muscular System: Structure, Function, and Physiology

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