Question 1

Which of the following is a unique feature of cardiac muscle tissue compared to skeletal and smooth muscle?

Accepted Answer

It is striated and involuntary.

Question 2

A patient is unable to maintain posture and body position due to a muscle disorder. Which muscle function is most directly affected?

Accepted Answer

Maintaining posture and body position

Question 3

Which connective tissue sheath surrounds individual muscle fibers in skeletal muscle?

Accepted Answer

Endomysium

Question 4

During a biceps curl, the biceps brachii muscle shortens as it lifts the weight. What type of contraction is this?

Accepted Answer

Concentric contraction

Question 5

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

Accepted Answer

It stores and releases calcium ions ($$Ca^{2+}).$$

Question 6

A muscle fiber is stimulated but does not change length, even though tension increases. What type of contraction is occurring?

Accepted Answer

Isometric contraction

Question 7

Which process is responsible for the initial depolarization of the sarcolemma during the generation of an action potential?

Accepted Answer

Simultaneous diffusion of $$Na^+$$ inward and $$K^+$$ outward

Question 8

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

Accepted Answer

Nerve impulse arrives, acetylcholine is released, acetylcholine binds to receptors, action potential is generated

Question 9

Which of the following is NOT a method by which ATP is regenerated during muscle activity?

Accepted Answer

Hydrolysis of lactic acid

Question 10

A marathon runner experiences muscle fatigue after prolonged exercise. Which of the following is LEAST likely to contribute to this fatigue?

Accepted Answer

Excess oxygen reserves in the muscle

Question 11

Which equation correctly represents the direct phosphorylation of ADP by creatine phosphate (CP) in muscle cells?

Accepted Answer

$$CP + ADP \rightarrow C + ATP$$

Question 12

Which structure anchors thin filaments and connects myofibrils to one another within a sarcomere?

Accepted Answer

Z disc

Question 13

A patient with a genetic defect in the protein tropomyosin would most likely have problems with which aspect of muscle contraction?

Accepted Answer

Binding of myosin to actin

Question 14

Which phase of a muscle twitch corresponds to the time when $$Ca^{2+} is re-$$entering the sarcoplasmic reticulum and muscle tension declines?

Accepted Answer

Period of relaxation

Question 15

Which of the following best explains why small motor units are found in muscles controlling the fingers and eyes?

Accepted Answer

They enable fine, precise movements.

Question 16

During intense exercise, oxygen delivery to muscle is impaired and pyruvic acid is converted to lactic acid. Which pathway is being utilized for ATP production?

Accepted Answer

Anaerobic glycolysis

Question 17

Which property of muscle tissue allows it to return to its original length after being stretched?

Accepted Answer

Elasticity

Question 18

Which of the following is TRUE regarding the sliding filament model of contraction?

Accepted Answer

Myosin heads bind to actin, detach, and rebind to propel thin filaments toward the M line.

Question 19

A muscle is stimulated repeatedly before it has completely relaxed, resulting in a sustained but quivering contraction. What is this phenomenon called?

Accepted Answer

Unfused (incomplete) tetanus

Question 20

Which of the following is a function of smooth muscle that distinguishes it from skeletal muscle?

Accepted Answer

It contracts in response to autonomic nerve fibers and can be self-excitatory.

Chapter 9: Muscles – Structure, Function, and Physiology

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