Podcast
Questions and Answers
Which characteristic distinguishes motor units in the thighs from those in the fingers?
Which characteristic distinguishes motor units in the thighs from those in the fingers?
- Thigh motor units contain fewer muscle fibers per neuron.
- Thigh motor units involve a single neuron innervating more muscle fibers. (correct)
- Finger motor units primarily control gross motor skills.
- Finger motor units are responsible for generating greater power.
What is the functional purpose of having smaller motor units in the fingers and eyes?
What is the functional purpose of having smaller motor units in the fingers and eyes?
- To allow for precise and finely controlled movements. (correct)
- To prevent fatigue during repetitive actions.
- To generate a large amount of force for powerful movements.
- To maintain muscle tone and posture.
How does the body increase the force produced by a muscle?
How does the body increase the force produced by a muscle?
- By decreasing the number of active motor units.
- By gradually activating more motor units in a process called recruitment. (correct)
- By initiating a single, powerful muscle twitch.
- By activating motor units on a fixed, non-rotating basis.
Why is summation necessary for skeletal muscle contraction?
Why is summation necessary for skeletal muscle contraction?
What is the primary purpose of motor units being activated on a rotating basis?
What is the primary purpose of motor units being activated on a rotating basis?
During normal muscular contractions, what physiological process leads to a state of tetanus?
During normal muscular contractions, what physiological process leads to a state of tetanus?
How does 'tone' contribute to maintaining body posture?
How does 'tone' contribute to maintaining body posture?
What is the immediate result of a motor unit being stimulated?
What is the immediate result of a motor unit being stimulated?
What is the functional difference between stimulating a few motor units versus stimulating many motor units in a muscle?
What is the functional difference between stimulating a few motor units versus stimulating many motor units in a muscle?
Which of the following best describes recruitment (multiple motor unit summation)?
Which of the following best describes recruitment (multiple motor unit summation)?
Flashcards
Motor Unit
Motor Unit
A nerve cell and all the muscle fibers it stimulates.
Tiny Motor Units
Tiny Motor Units
Eyes and fingers have these, providing precise and accurate movements.
Large Motor Units
Large Motor Units
Thighs and gluteal muscles have these, generating great power.
Motor Unit Recruitment
Motor Unit Recruitment
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Muscle Twitch
Muscle Twitch
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Summation
Summation
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Tetanus
Tetanus
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Recruitment
Recruitment
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Motor Unit Rotation
Motor Unit Rotation
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Muscle Tone
Muscle Tone
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Study Notes
- Motor units consist of a nerve cell (nerve fiber) and all the muscle fibers it stimulates.
- Tiny motor units in areas like the eyes and fingers allow for fine motor control.
- Small motor units may have one neuron connected to only 1-3 muscle fibers.
- Large motor units in the thighs and gluteal muscles consist of one neuron stimulating up to 2000 muscle fibers.
- Activating more motor units increases the force generated by a muscle.
Muscle Stimulation and Contraction
- Skeletal muscles contract when their motor units are stimulated.
- A single contraction is called a muscle twitch.
- A muscle twitch involves a single stimulus-contraction-relaxation sequence that lasts a fraction of a second.
- Muscle cells must be repeatedly stimulated in a process called summation to do work.
- Repeated stimulation without full relaxation leads to increased tension, peaking during normal muscular contractions.
- Tetanus is a state of sustained maximal contraction.
- Recruitment, or multiple motor unit summation, involves the gradual activation of more motor units to increase muscle tension.
- Motor units are activated on a rotating basis to reduce fatigue.
- Tone is a continuous, partial contraction of alternate muscle fibers that gives muscles a firm appearance and prevents collapse during sleep.
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