Question 1

Which of the following statements best distinguishes skeletal muscle from cardiac and smooth muscle tissue?

Accepted Answer

Skeletal muscle is voluntary, striated, and attached to bones for movement.

Question 2

A patient suffers from a condition that impairs the function of their sarcoplasmic reticulum (SR) in skeletal muscle fibers. Which physiological process would be most directly affected?

Accepted Answer

The storage and release of calcium ions ($\mathrm{Ca^{2+}}$) necessary for muscle contraction.

Question 3

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

Accepted Answer

Endomysium

Question 4

During the sliding filament model of muscle contraction, which event occurs immediately after myosin heads bind to actin?

Accepted Answer

The myosin head pivots, pulling the actin filament toward the center of the sarcomere.

Question 5

Which of the following best describes the function of T tubules in skeletal muscle fibers?

Accepted Answer

They allow electrical impulses to travel deep into the muscle fiber, ensuring simultaneous contraction.

Question 6

A patient is unable to consciously control the contraction of a certain muscle. Which type of muscle tissue is most likely involved?

Accepted Answer

Cardiac muscle

Question 7

Which of the following is a major function of the muscular system?

Accepted Answer

Maintaining posture and body position

Question 8

Which structure is the smallest contractile unit of a skeletal muscle fiber?

Accepted Answer

Sarcomere

Question 9

A toxin blocks the voltage-gated calcium channels at the axon terminal of a motor neuron. What is the most immediate effect on muscle contraction?

Accepted Answer

Acetylcholine will not be released into the synaptic cleft.

Question 10

Which of the following best explains why cardiac muscle can contract without nervous system stimulation?

Accepted Answer

Cardiac muscle contains its own pacemaker cells that generate action potentials.

Question 11

Which of the following is true regarding the arrangement of myofilaments in a sarcomere?

Accepted Answer

Actin filaments are thin and anchored to the Z disc, while myosin filaments are thick and span the A band.

Question 12

A patient presents with muscle weakness. Laboratory tests reveal a deficiency in acetylcholinesterase at the neuromuscular junction. Which of the following symptoms would most likely be observed?

Accepted Answer

Prolonged muscle contraction due to excess acetylcholine in the synaptic cleft.

Question 13

Which of the following best describes an indirect attachment of skeletal muscle to bone?

Accepted Answer

Connective tissue wrappings extend beyond the muscle as a tendon or aponeurosis.

Question 14

Which of the following events occurs first at the neuromuscular junction to initiate muscle contraction?

Accepted Answer

Voltage-gated calcium channels open in the axon terminal.

Question 15

A muscle fiber is unable to contract even though acetylcholine is released and binds to its receptors. Which of the following is the most likely cause?

Accepted Answer

The sarcoplasmic reticulum fails to release $\mathrm{Ca^{2+}}$.

Question 16

Which of the following best explains why smooth muscle is able to sustain contractions for longer periods without fatigue compared to skeletal muscle?

Accepted Answer

Smooth muscle contracts involuntarily and uses less ATP per contraction.

Question 17

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

Accepted Answer

Action potential arrives at axon terminal → Voltage-gated calcium channels open → Acetylcholine released → Acetylcholine binds to receptors → Sodium enters muscle fiber

Question 18

A muscle biopsy reveals a high density of myofibrils and multiple peripheral nuclei per cell. Which type of muscle tissue is most likely present?

Accepted Answer

Skeletal muscle

Question 19

Which of the following best describes the role of ATP in the sliding filament model of muscle contraction?

Accepted Answer

ATP hydrolysis provides energy for the myosin head to detach from actin and reset for another power stroke.

Muscles and Muscle Tissue: Structure, Function, and Physiology

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