Podcast
Questions and Answers
What does a motor unit consist of?
What does a motor unit consist of?
- Only muscle fibers that contract independently
- Sensory neurons and muscle fibers
- The anterior motor neuron and specific muscle fibers it innervates (correct)
- Multiple motor neurons and muscle fibers
How does the number of muscle fibers per motor neuron relate to a muscle's function?
How does the number of muscle fibers per motor neuron relate to a muscle's function?
- It generally relates to how much strength is needed
- The number is constant regardless of function
- It generally relates to the muscle's particular movement function (correct)
- It generally increases with greater precision of movement required
What is the All-or-None Principle in relation to motor units?
What is the All-or-None Principle in relation to motor units?
- All muscle fibers in a motor unit contract or none do (correct)
- Motor units can vary in their contraction strength
- Some muscle fibers may contract while others do not
- A stronger stimulus causes a stronger contraction
What is true about muscle fibers receiving input from a motor neuron?
What is true about muscle fibers receiving input from a motor neuron?
Which statement best describes motor neurons' ability to control muscle contractions?
Which statement best describes motor neurons' ability to control muscle contractions?
Flashcards
Motor Unit
Motor Unit
A motor neuron and the muscle fibers it controls.
All-or-None Principle
All-or-None Principle
A motor neuron either fully activates or completely ignores its muscle fibers.
Motor Neuron
Motor Neuron
A nerve cell that sends signals to muscle fibers.
Muscle Fiber
Muscle Fiber
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Precision Movement
Precision Movement
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Study Notes
Motor Unit Structure
- Motor unit comprises the anterior motor neuron and the specific muscle fibers it innervates.
- Each muscle fiber typically receives input from only one neuron.
- However, a single motor neuron can innervate multiple muscle fibers.
- The number of muscle fibers per motor neuron is related to the muscle's function.
- Muscles demanding less precision have hundreds of fibers per motor neuron.
- Muscles requiring fine control have one muscle fiber per motor neuron.
All-or-None Principle
- Sufficient stimulus to trigger an action potential in the motor neuron causes all muscle fibers in the motor unit to contract simultaneously.
- No partial activation of muscle fibers is possible.
- A motor unit generates either full contraction or no contraction, no gradation of force.
- Stronger action potentials do not produce stronger contractions within a single motor unit.
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