Q: Which equation best represents the mechanical advantage of a lever system in the human body?

$$MA = \frac{\text{Length of effort arm}}{\text{Length of load arm}}$$

Question 1

Which of the following best explains why slow-twitch (type I) muscle fibers are more fatigue-resistant than fast-twitch glycolytic (type IIB/X) fibers?

Accepted Answer

They have a higher density of mitochondria and rely primarily on oxidative phosphorylation for ATP production.

Question 2

A sprinter is performing a 100-meter dash. Which muscle fiber type is most heavily recruited during this activity, and why?

Accepted Answer

Fast-twitch glycolytic fibers (type IIB/X), because they generate rapid, powerful contractions using anaerobic glycolysis.

Question 3

Which of the following statements about the length-tension relationship in skeletal muscle is correct?

Accepted Answer

Maximum tension is generated when sarcomeres are at their optimal resting length, allowing for maximal crossbridge formation.

Question 4

A patient is unable to maintain muscle contraction during repetitive activity and experiences rapid fatigue. Which muscle fiber type is most likely deficient?

Accepted Answer

Slow-twitch oxidative fibers (type I)

Question 5

During an isometric contraction, which of the following occurs at the level of the sarcomere and the whole muscle?

Accepted Answer

Sarcomeres shorten, but the overall muscle length remains unchanged due to stretching of series elastic elements.

Question 6

Which equation best represents the mechanical advantage of a lever system in the human body?

Accepted Answer

$$MA = \frac{	ext{Length of effort arm}}{	ext{Length of load arm}}$$

Question 7

A muscle is stimulated by a series of action potentials so rapidly that it does not relax between stimuli, resulting in a sustained maximal contraction. What is this phenomenon called?

Accepted Answer

Complete (fused) tetanus

Question 8

Which of the following best describes the function of the Golgi tendon organ (GTO)?

Accepted Answer

It senses changes in muscle tension and helps prevent excessive force generation that could damage the muscle.

Question 9

Which of the following is true regarding asynchronous recruitment of motor units?

Accepted Answer

It helps delay muscle fatigue by allowing some motor units to rest while others are active.

Question 10

A person is holding a heavy box stationary at waist level. Which type of muscle contraction is primarily occurring in the biceps brachii?

Accepted Answer

Isometric contraction

Question 11

Which of the following best explains why fast-twitch glycolytic fibers (type IIB/X) appear pale compared to slow-twitch fibers?

Accepted Answer

They contain less myoglobin and fewer mitochondria.

Question 12

During a biceps curl, as the weight is lifted, which type of contraction occurs in the biceps muscle?

Accepted Answer

Concentric isotonic contraction

Question 13

Which of the following best describes the role of muscle spindles?

Accepted Answer

They detect changes in muscle length and initiate the stretch reflex.

Question 14

A patient presents with a loss of muscle tone and an inability to maintain posture. Which structure is most likely impaired?

Accepted Answer

Muscle spindles

Question 15

Which of the following is a correct sequence of events in the stretch reflex involving alpha-gamma coactivation?

Accepted Answer

Alpha and gamma motor neurons are activated simultaneously; extrafusal fibers contract; intrafusal fibers contract; muscle spindle remains sensitive.

Question 16

Which of the following best describes the effect of increasing the number of active motor units during a muscle contraction?

Accepted Answer

It increases the total force generated by the muscle.

Question 17

A person is slowly lowering a heavy object to the ground. Which type of muscle contraction is occurring in the biceps brachii during this movement?

Accepted Answer

Eccentric isotonic contraction

Question 18

Which of the following best explains why oxidative muscle fibers have a higher endurance capacity?

Accepted Answer

They have more mitochondria and myoglobin, allowing for sustained aerobic ATP production.

Question 19

Which of the following is true regarding the relationship between load and contraction velocity in skeletal muscle?

Accepted Answer

As the load increases, the velocity of muscle contraction decreases.

Question 20

Which of the following best describes the function of series elastic elements in muscle contraction?

Accepted Answer

They allow sarcomeres to shorten while the overall muscle length remains constant during isometric contractions.

Skeletal Muscle: Structure, Function, and Mechanics

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