Question 1

Which of the following best describes the 'latent period' of a muscle twitch?

Accepted Answer

The time between the application of a stimulus and the beginning of contraction, when Ca$$^{2+} is $$released from the sarcoplasmic reticulum.

Question 2

A patient is unable to generate strong muscle contractions despite normal nerve stimulation. Which of the following is the most likely explanation based on the 'all or none' principle?

Accepted Answer

The muscle fibers are only partially contracting due to subthreshold stimuli.

Question 3

Which scenario would most likely result in complete (fused) tetanus in a skeletal muscle?

Accepted Answer

Rapid, repeated stimuli with no relaxation between contractions.

Question 4

What is the primary reason that increasing the frequency of neuronal stimulation increases muscle tension?

Accepted Answer

It allows more Ca$$^{2+} to $$accumulate in the sarcoplasm, enhancing cross-bridge formation.

Question 5

Which of the following best explains why a muscle that is overly stretched before contraction produces less force?

Accepted Answer

There are fewer cross-bridges formed due to less overlap of actin and myosin filaments.

Question 6

A muscle is stimulated to contract, but the contraction is weak. Which of the following could explain this observation?

Accepted Answer

The muscle is either too stretched or too compressed, reducing cross-bridge formation.

Question 7

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

Accepted Answer

It is longer in cardiac muscle (about 300 ms) than in skeletal muscle (about 5 ms).

Question 8

Which of the following best describes muscle tone?

Accepted Answer

Some muscle fibers in every muscle are contracted at any given time, even at rest.

Question 9

A patient has experienced nerve damage resulting in a lack of stimulation to a muscle. What is the most likely outcome?

Accepted Answer

Muscle atrophy due to loss of myofibrils and replacement by fibrous tissue.

Question 10

Which of the following would increase the overall force of contraction in a whole muscle?

Accepted Answer

Increasing the number of motor units recruited.

Question 11

During which phase of a muscle twitch is Ca$$^{2+}$$ actively transported back into the sarcoplasmic reticulum?

Accepted Answer

Relaxation period

Question 12

Which of the following best explains why larger motor units generate stronger contractions?

Accepted Answer

They contain more muscle fibers per motor neuron.

Question 13

Which of the following is a characteristic of incomplete (unfused) tetanus?

Accepted Answer

Muscle partially relaxes between stimuli, resulting in fluctuating tension.

Question 14

Which of the following is NOT a way to increase the strength of a muscle contraction?

Accepted Answer

Decreasing the overlap of actin and myosin filaments.

Question 15

Which of the following best describes muscle hypertrophy?

Accepted Answer

Increase in muscle size due to increased myofibrils, mitochondria, and sarcoplasmic reticulum.

Question 16

A muscle is producing maximum tension during a sustained contraction. What is happening at the cellular level?

Accepted Answer

There is perfect overlap of actin and myosin filaments, allowing maximum cross-bridge formation.

Question 17

Which of the following is true about the regulation of force in a single motor unit?

Accepted Answer

All fibers in a motor unit contract fully if the threshold stimulus is reached.

Question 18

Which of the following best explains why motor units take turns contracting during sustained muscle contractions?

Accepted Answer

To allow some muscle fibers to rest and prevent fatigue.

Question 19

Which of the following is a direct result of the 'all or none' principle in skeletal muscle fibers?

Accepted Answer

A muscle fiber contracts maximally if the threshold stimulus is reached.

Muscle Tension and Regulation of Muscle Contraction

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