Muscle Contraction

Interactive Lecture

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​Muscle
Contraction

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Multiple Choice

Which of the following best describes a concentric contraction?

• The muscle elongates while producing force

• The muscle contracts without changing length

• The muscle shortens while producing force

• The muscle remains relaxed and passive

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Open Ended

Explain the difference between isotonic and isometric contractions.

Multiple Choice

Which muscle acts as the prime mover (agonist) during the flexion of the elbow?

• Triceps brachii

• Brachioradialis

• Brachialis

• Biceps brachii

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Multiple Choice

Which system controls the activities of skeletal muscles?

• Autonomic nervous system

• Somatic motor nervous system

• Central nervous system

• Endocrine system

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Multiple Choice

What defines a motor unit?

• A single muscle fiber

• A motor neuron and all the muscle fibers it innervates

• A group of motor neurons

• A single axon terminal

Open Ended

Explain how the size of a motor unit affects muscle control and provide examples of activities that involve small and large motor units.

Multiple Choice

What are the three phases of a muscle twitch as

recorded on a myogram?

• Latent period, contraction phase, relaxation phase

• Initiation phase, action phase, recovery phase

• Stimulation phase, active phase, resting phase

• Onset period, peak phase, decline phase

Multiple Choice

Which of the following mechanisms is used to produce graded muscle responses?

• Increasing muscle fiber size

• Changing the frequency of stimulation and the number of motor units stimulated

• Decreasing the number of muscle fibers

• Altering the type of muscle fiber

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Match

Match the type of stimulus with its effect

• Subthreshold

• Threshold

• Maximal

No observable muscle contraction

Weak contraction produced

Strong contraction produced

• No observable muscle contraction

• Weak contraction produced

• Strong contraction produced

Multiple Choice

What is the primary function of muscle tone?

• To produce active movement

• To keep muscles firm, healthy, and ready to respond

• To increase muscle size

• To decrease muscle fatigue

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Poll

How do you feel right now?