Question 1

Which of the following best describes a motor unit in skeletal muscle?

Accepted Answer

A motor neuron and all the muscle fibers it innervates

Question 2

During which phase of a muscle twitch does calcium re-enter the sarcoplasmic reticulum, causing muscle tension to decline?

Accepted Answer

Period of relaxation

Question 3

A patient is unable to lift a heavy box, but their muscles are visibly contracting without changing length. What type of contraction is occurring?

Accepted Answer

Isometric contraction

Question 4

Which of the following factors does NOT increase the force of skeletal muscle contraction?

Accepted Answer

Stretching the sarcomere to 170% of its resting length

Question 5

What is the physiological basis for wave (temporal) summation in skeletal muscle?

Accepted Answer

Muscle fibers are stimulated in rapid succession before they fully relax

Question 6

Which of the following best explains why a muscle contracts more forcefully when its sarcomeres are at 100% of their resting length?

Accepted Answer

There is maximal overlap between actin and myosin filaments, allowing optimal cross-bridge formation

Question 7

A muscle is stimulated with increasing voltage. At a certain point, no further increase in contraction strength is observed. What is this point called?

Accepted Answer

Maximal stimulus

Question 8

Which of the following scenarios best illustrates an isotonic eccentric contraction?

Accepted Answer

Lowering a book slowly onto a table

Question 9

If a muscle is repeatedly stimulated at a high frequency so that no relaxation occurs between stimuli, what is the resulting contraction called?

Accepted Answer

Fused (complete) tetanus

Question 10

Which of the following is a direct result of increased recruitment during muscle contraction?

Accepted Answer

Increased force of contraction

Question 11

A muscle fiber is stimulated by a single action potential. Which of the following best describes the resulting contraction?

Accepted Answer

Muscle twitch

Question 12

Which of the following best explains why muscle tone is important in the human body?

Accepted Answer

It keeps muscles firm, healthy, and ready to respond to stimulation

Question 13

Which of the following is true regarding the period of contraction in a muscle twitch?

Accepted Answer

It is the time when cross-bridges are actively forming and muscle tension increases

Question 14

Which of the following would most likely result in a decrease in the force of muscle contraction?

Accepted Answer

Decreasing the frequency of stimulation

Question 15

A patient is experiencing muscle fatigue after prolonged contraction. Which of the following best explains this phenomenon?

Accepted Answer

ATP reserves are depleted and metabolic byproducts accumulate

Question 16

Which of the following best describes the relationship between the number of muscle fibers in a motor unit and the precision of muscle control?

Accepted Answer

Smaller motor units provide greater fine control

Question 17

Which of the following is a characteristic of an isometric contraction?

Accepted Answer

The muscle generates tension but does not change length

Question 18

Which of the following best explains why a muscle that is stretched to 150% of its resting length produces less force?

Accepted Answer

There is insufficient overlap between actin and myosin filaments for cross-bridge formation

Question 19

Which of the following is the correct sequence of events in a muscle twitch?

Accepted Answer

Latent period → period of contraction → period of relaxation

Question 20

A muscle is stimulated by a series of rapid stimuli, resulting in a smooth, sustained contraction with no evidence of relaxation. What is this phenomenon called?

Accepted Answer

Fused (complete) tetanus

Muscle Contraction: Ch 9C Properties, Mechanisms, and Factors in Skeletal Muscle

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