Question 1

Which of the following best describes the role of myoglobin in skeletal muscle fibers?

Accepted Answer

It binds oxygen, allowing aerobic metabolism during muscle activity.

Question 2

During the sliding filament mechanism of muscle contraction, which event directly follows the binding of calcium to troponin?

Accepted Answer

Tropomyosin moves, exposing active sites on actin.

Question 3

A patient is unable to relax their muscles after death, resulting in rigor mortis. What does this indicate about ATP and cross-bridge detachment?

Accepted Answer

ATP is necessary for myosin heads to detach from actin.

Question 4

Which connective tissue layer surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 5

What is the primary function of the sarcoplasmic reticulum in skeletal muscle cells?

Accepted Answer

To store and release calcium ions during contraction.

Question 6

Which of the following best explains why slow oxidative muscle fibers are fatigue-resistant?

Accepted Answer

They contain many mitochondria and rely on aerobic respiration.

Question 7

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

Accepted Answer

Isometric contraction

Question 8

Which of the following is TRUE regarding the neuromuscular junction?

Accepted Answer

The synaptic cleft is the site where acetylcholine binds to receptors on the sarcolemma.

Question 9

Which equation represents the direct phosphorylation of ADP by creatine phosphate in muscle cells?

Accepted Answer

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

Question 10

Which of the following muscle types is best suited for endurance activities such as marathon running?

Accepted Answer

Slow oxidative fibers

Question 11

During muscle contraction, which band or zone does NOT change in width?

Accepted Answer

A band

Question 12

Which of the following is a property unique to smooth muscle compared to skeletal muscle?

Accepted Answer

Ability to undergo hyperplasia (increase in cell number)

Question 13

What is the optimal length-tension relationship for skeletal muscle contraction?

Accepted Answer

When the muscle is slightly stretched, allowing maximal cross-bridge formation

Question 14

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

Accepted Answer

Degradation by acetylcholinesterase

Question 15

Which of the following best describes the latent period in excitation-contraction coupling?

Accepted Answer

The time between the arrival of the action potential and the onset of muscle tension

Question 16

Which of the following is the first energy source used to regenerate ATP during intense muscle activity?

Accepted Answer

Creatine phosphate

Question 17

Which of the following is TRUE regarding muscle fatigue?

Accepted Answer

It results from a relative deficit of ATP and ionic imbalances.

Question 18

Which of the following events occurs during the power stroke of muscle contraction?

Accepted Answer

Myosin heads bind to actin and pull thin filaments toward the center of the sarcomere.

Question 19

Which of the following is a feature of multi-unit smooth muscle?

Accepted Answer

Each muscle fiber is structurally independent and richly supplied with nerve endings.

Question 20

Which of the following is TRUE about the role of ATP in muscle contraction and relaxation?

Accepted Answer

ATP is required for both cross-bridge detachment and the reuptake of calcium into the sarcoplasmic reticulum.

Physiology of Muscle: Structure, Function, and Comparison of Muscle Types

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