Question 1

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

Accepted Answer

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

Question 2

During the sliding filament mechanism of skeletal muscle contraction, which event directly requires ATP?

Accepted Answer

Detachment of myosin heads from actin filaments.

Question 3

A patient is experiencing muscle fatigue after intense exercise. Which of the following is most likely contributing to this fatigue?

Accepted Answer

Relative deficit of ATP and accumulation of lactic acid.

Question 4

Which connective tissue layer surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 5

What is the primary function of myoglobin in skeletal muscle cells?

Accepted Answer

To store oxygen for aerobic metabolism.

Question 6

Which of the following best explains why eccentric isotonic contractions are more likely to cause delayed-onset muscle soreness than concentric contractions?

Accepted Answer

Eccentric contractions generate more force and cause greater microtrauma to muscle fibers.

Question 7

Which of the following is TRUE regarding the optimal length-tension relationship in skeletal muscle?

Accepted Answer

Maximum contractile force is generated when the muscle is slightly stretched, allowing optimal crossbridge formation.

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 events occurs FIRST during excitation-contraction coupling at the neuromuscular junction?

Accepted Answer

Acetylcholine binds to receptors on the sarcolemma.

Question 10

Which muscle fiber type is best suited for endurance activities such as marathon running?

Accepted Answer

Slow oxidative fibers

Question 11

Which of the following is a major difference between smooth muscle and skeletal muscle?

Accepted Answer

Smooth muscle contraction is regulated by calmodulin instead of troponin.

Question 12

Which process is responsible for the termination of acetylcholine action at the neuromuscular junction?

Accepted Answer

Enzymatic breakdown by acetylcholinesterase ($\mathrm{AChE}$)

Question 13

During a rapid series of nerve impulses, a muscle fiber is unable to relax between stimuli, resulting in a sustained contraction. What is this phenomenon called?

Accepted Answer

Tetanus

Question 14

Which of the following is the correct sequence of events in the crossbridge cycle during muscle contraction?

Accepted Answer

Myosin binds to actin, power stroke occurs, ADP and $\mathrm{P_i}$ are released, ATP binds to myosin, myosin detaches from actin.

Question 15

Which energy source is used FIRST to regenerate ATP during short, intense muscle activity?

Accepted Answer

Creatine phosphate

Question 16

Which of the following best describes the effect of increasing load on the velocity and duration of skeletal muscle contraction?

Accepted Answer

Greater load results in slower contraction velocity and shorter contraction duration.

Question 17

Which of the following statements about muscle tone is correct?

Accepted Answer

Muscle tone is the partial, involuntary contraction of muscles due to reflex activity.

Question 18

Which of the following is TRUE regarding the role of calcium ions ($\mathrm{Ca^{2+}}$) in smooth muscle contraction?

Accepted Answer

Calcium binds to calmodulin, which activates myosin light chain kinase for crossbridge formation.

Question 19

Which of the following is a characteristic of multiunit smooth muscle?

Accepted Answer

Muscle fibers are structurally independent and rarely have gap junctions.

Physiology of Muscle: Structure, Function, and Types

Study Guide - Practice Questions

Study Guide - Flashcards