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. Which muscle is most likely impaired?

Accepted Answer

Biceps brachii

Question 3

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

Accepted Answer

Cross-bridge cycling between actin and myosin increases, generating maximum tension.

Question 4

Which of the following statements about fast-twitch (white) muscle fibers is correct?

Accepted Answer

They fatigue quickly due to reliance on glycolysis for ATP production.

Question 5

What is the primary function of the Z line in a sarcomere?

Accepted Answer

It marks the boundary between adjacent sarcomeres and anchors thin filaments.

Question 6

A muscle is contracting but not changing length while pushing against an immovable object. What type of contraction is this?

Accepted Answer

Isometric contraction

Question 7

Which of the following best explains why cardiac muscle cannot undergo tetanus?

Accepted Answer

Cardiac muscle cells have long refractory periods that prevent sustained contraction.

Question 8

Which process provides the majority of ATP for a muscle fiber during moderate, sustained activity?

Accepted Answer

Aerobic metabolism in the mitochondria

Question 9

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 leads to smaller and weaker muscle fibers.

Question 10

Which of the following equations correctly represents the reaction catalyzed by creatine phosphokinase (CPK) during muscle contraction?

Accepted Answer

$$\mathrm{CP + ADP \rightarrow ATP + Creatine}$$

Question 11

Which of the following is a function of the pelvic floor muscles?

Accepted Answer

Support the organs of the pelvic cavity and control movement through the anus and urethra.

Question 12

Which muscle is the prime mover (agonist) for abduction of the arm at the shoulder?

Accepted Answer

Deltoid

Question 13

A patient presents with difficulty extending their knee. Which muscle group is most likely affected?

Accepted Answer

Quadriceps femoris

Question 14

Which of the following best describes the sliding filament theory of muscle contraction?

Accepted Answer

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

Question 15

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 16

Which of the following best explains why smooth muscle can contract over a greater range of lengths than skeletal muscle?

Accepted Answer

Actin and myosin filaments are not rigidly organized in smooth muscle.

Question 17

Which of the following best describes the function of a synergist muscle?

Accepted Answer

It assists the prime mover in performing a movement.

Question 18

Which of the following is a correct description of muscle tone?

Accepted Answer

It is the resting tension in skeletal muscle that stabilizes bones and joints.

Question 19

Which of the following best explains the difference between isotonic and isometric contractions?

Accepted Answer

Isotonic contractions change muscle length, while isometric contractions do not change muscle length.

Question 20

Which of the following is a likely effect of aging on skeletal muscle?

Accepted Answer

Skeletal muscle fibers become smaller in diameter and less elastic.

The Muscular System: Structure, Function, and Physiology

Study Guide - Practice Questions