Question 1

Which of the following statements best describes the structural differences between skeletal, cardiac, and smooth muscle cells?

Accepted Answer

Skeletal muscle cells are multinucleate and striated, cardiac muscle cells are branching and have intercalated discs, and smooth muscle cells are spindle-shaped and lack striations.

Question 2

Which connective tissue wrapping surrounds an individual muscle fiber in skeletal muscle?

Accepted Answer

Endomysium

Question 3

A patient is experiencing muscle fatigue after prolonged exercise. Which of the following is NOT a likely contributing factor?

Accepted Answer

Increased ATP production

Question 4

Which muscle type is responsible for voluntary movements such as lifting weights?

Accepted Answer

Skeletal muscle

Question 5

During muscle contraction, which ion is released from the sarcoplasmic reticulum and acts as the final trigger for contraction?

Accepted Answer

Ca$$^{2+}$$

Question 6

Which of the following best describes the role of acetylcholine (ACh) at the neuromuscular junction?

Accepted Answer

ACh binds to receptors on the sarcolemma, initiating an action potential in the muscle fiber.

Question 7

Which pathway provides the greatest net gain of ATP per glucose molecule during muscle activity?

Accepted Answer

Aerobic cellular respiration

Question 8

A person is holding a heavy box without moving it. Which type of muscle contraction is primarily occurring?

Accepted Answer

Isometric contraction

Question 9

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

Accepted Answer

Presence of intercalated discs

Question 10

Which of the following best explains why aerobic exercise improves muscle endurance?

Accepted Answer

It increases the efficiency of aerobic respiration, allowing muscles to produce more ATP over longer periods.

Question 11

Which structure is the functional unit of skeletal muscle contraction?

Accepted Answer

Sarcomere

Question 12

Which of the following is true regarding the sliding filament theory of muscle contraction?

Accepted Answer

Myosin heads bind to actin, pulling the thin filaments toward the center of the sarcomere.

Question 13

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

Accepted Answer

It stores and releases calcium ions needed for contraction.

Question 14

Which of the following is a characteristic of smooth muscle but NOT of skeletal or cardiac muscle?

Accepted Answer

Spindle-shaped, uninucleate cells with no striations

Question 15

A muscle fiber is stimulated by a motor neuron. Which of the following best describes the sequence of events leading to contraction?

Accepted Answer

ACh is released, binds to sarcolemma receptors, Na$$^+$$ enters, action potential is generated, Ca$$^{2+} is $$released from SR.

Question 16

Which of the following best explains why muscle tone is important for overall health?

Accepted Answer

It keeps muscles firm, healthy, and ready for action by maintaining continuous partial contractions.

Question 17

Which of the following is the only energy source that can be used directly to power muscle contraction?

Accepted Answer

ATP

Question 18

Which of the following best describes the effect of resistance (isometric) exercise on muscles?

Accepted Answer

It increases muscle size and strength by enlarging individual muscle fibers.

Question 19

Which of the following is a correct statement about the connective tissue components of muscle types?

Accepted Answer

Skeletal muscle contains epimysium, perimysium, and endomysium; cardiac muscle contains only endomysium; smooth muscle contains only endomysium.

Question 20

A marathon runner relies on which primary pathway for ATP regeneration during a race?

Accepted Answer

Aerobic cellular respiration

The Muscular System: Structure, Function, and Physiology

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