Question 1

Which phase of a muscle fiber twitch is characterized by the propagation of the action potential across the sarcolemma and the release of Ca$$^{2+}$$ from the sarcoplasmic reticulum?

Accepted Answer

Latent period

Question 2

During which type of muscle contraction does the muscle length remain constant because the external force equals the force generated by the muscle?

Accepted Answer

Isometric contraction

Question 3

What is the primary factor that determines the total tension produced by a single muscle fiber?

Accepted Answer

The frequency of action potential firing by the motor neuron

Question 4

If a muscle fiber is stimulated repeatedly and does not have time to fully relax between twitches, what phenomenon occurs?

Accepted Answer

Wave summation

Question 5

Which equation best represents the relationship between muscle tension ($$T$$), number of motor units recruited ($$N$$), and frequency of action potential firing ($$f$$)?

Accepted Answer

$$T = N 	imes f$$

Question 6

A patient is unable to generate maximal muscle tension despite repeated stimulation. Which of the following is the most likely explanation?

Accepted Answer

The muscle fiber is overly stretched or overly shortened

Question 7

Which of the following best describes the recruitment and motor unit size principle?

Accepted Answer

Smaller motor units are recruited first, then larger ones as force requirements increase

Question 8

In which scenario would you expect to find the smallest motor units?

Accepted Answer

Muscles responsible for fine motor control, such as the eye muscles

Question 9

Which of the following statements about fused tetanus is correct?

Accepted Answer

Tension reaches 100% of maximum and the muscle does not relax between stimuli

Question 10

A muscle is stretched beyond its optimal length. What happens to the tension it can generate?

Accepted Answer

Tension decreases below maximal

Question 11

Which of the following best explains why a muscle fiber at optimal sarcomere length generates maximal tension?

Accepted Answer

All myosin heads are able to bind to actin, maximizing cross-bridge formation

Question 12

Which of the following is true regarding motor units?

Accepted Answer

One motor neuron innervates multiple muscle fibers

Question 13

During isotonic eccentric contraction, which of the following occurs?

Accepted Answer

Muscle lengthens as external force is greater than force generated by muscle

Question 14

Which of the following best describes the process of wave summation?

Accepted Answer

Repeated stimulation causes progressively greater tension production if the fiber does not fully relax between twitches

Question 15

A muscle fiber twitch is recorded using a myogram. Which phase is associated with the pumping of Ca$$^{2+}$$ ions back into the sarcoplasmic reticulum?

Accepted Answer

Relaxation period

Question 16

Which of the following is a real-life example of an isometric contraction?

Accepted Answer

Holding a heavy object steady without moving your arm

Question 17

If a person is performing a bicep curl and the muscle shortens while lifting the weight, which type of contraction is occurring?

Accepted Answer

Isotonic concentric contraction

Question 18

Which of the following best describes the length-tension relationship in skeletal muscle?

Accepted Answer

Muscle tension is highest at optimal sarcomere length

Question 19

Which of the following is true regarding the recruitment of motor units during increasing force requirements?

Accepted Answer

Smaller motor units are recruited first, followed by larger motor units as force increases

Question 20

Which of the following best explains why fine motor control muscles, such as those in the eye, have smaller motor units?

Accepted Answer

Smaller motor units allow for more precise and controlled movements

Muscle Tension and Contraction: Mechanisms and Principles (M2)

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