Question 1

Which of the following best describes the structure of a motor unit?

Accepted Answer

A single motor neuron and all the muscle fibers it innervates

Question 2

What is the primary function of a motor unit in skeletal muscle contraction?

Accepted Answer

To coordinate the contraction of a group of muscle fibers in response to a single motor neuron

Question 3

A single motor neuron innervates 150 muscle fibers. What is this group collectively called?

Accepted Answer

A motor unit

Question 4

Which of the following best explains why fine motor control (such as in the fingers) requires smaller motor units?

Accepted Answer

Smaller motor units allow for more precise and graded muscle contractions

Question 5

If a disease destroys motor neurons, what is the most likely effect on muscle tension?

Accepted Answer

Muscle tension will decrease because fewer muscle fibers are innervated

Question 6

Which of the following equations best represents the relationship between the number of active motor units ($$n) $$and total muscle tension ($$T$$)?

Accepted Answer

$$T = n 	imes F_{fiber}$$

Question 7

During a muscle contraction, what happens if more motor units are recruited?

Accepted Answer

The muscle produces more tension

Question 8

Which scenario best illustrates the 'all-or-none' principle of motor unit activation?

Accepted Answer

A motor neuron fires, causing all its associated muscle fibers to contract fully

Question 9

Why do larger muscles, such as those in the thigh, have larger motor units compared to muscles controlling the eyes?

Accepted Answer

Larger muscles require more force and less precise control

Question 10

A patient presents with muscle weakness and electromyography reveals reduced motor unit recruitment. Which of the following is the most likely explanation?

Accepted Answer

Decreased number of functioning motor neurons

Muscle Tension at the Organ Level: Motor Units

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