Podcast
Questions and Answers
What is the primary difference between motor units in the eyes and fingers compared to those in the thighs and gluteal muscles?
What is the primary difference between motor units in the eyes and fingers compared to those in the thighs and gluteal muscles?
- Motor units in the eyes and fingers provide fine motor control, while those in the thighs and gluteal muscles generate great power. (correct)
- Motor units in the thighs and gluteal muscles have finer motor control.
- Motor units in the eyes and fingers contain more neurons per muscle fiber.
- Motor units in the thighs and gluteal muscles contain fewer muscle fibers per neuron.
Which of the following best describes the relationship between motor unit size and motor control?
Which of the following best describes the relationship between motor unit size and motor control?
- Motor unit size has no impact on the precision of motor control.
- Larger motor units enable more precise and controlled movements.
- Smaller motor units enable finer and more controlled movements. (correct)
- Motor unit size only affects the speed of muscle contractions.
What is the result of repeated stimulation of a muscle without full relaxation?
What is the result of repeated stimulation of a muscle without full relaxation?
- Summation, leading to increased tension that can plateau into tetanus. (correct)
- Muscle fatigue and immediate failure.
- A single muscle twitch.
- A decrease in overall muscle tension.
How does the body increase the amount of force produced by a muscle?
How does the body increase the amount of force produced by a muscle?
Why are motor units activated on a rotating basis?
Why are motor units activated on a rotating basis?
What is muscle tone, and what purpose does it serve?
What is muscle tone, and what purpose does it serve?
During a sustained muscle contraction, what physiological process prevents muscle fatigue?
During a sustained muscle contraction, what physiological process prevents muscle fatigue?
Which of the following accurately describes the sequence of events in muscle contraction, starting from motor unit stimulation?
Which of the following accurately describes the sequence of events in muscle contraction, starting from motor unit stimulation?
How does the number of activated motor units correlate with the force generated by a muscle?
How does the number of activated motor units correlate with the force generated by a muscle?
What distinguishes 'tetanus' as a physiological state from the disease also known as 'tetanus'?
What distinguishes 'tetanus' as a physiological state from the disease also known as 'tetanus'?
Flashcards
What is a motor unit?
What is a motor unit?
A nerve cell and all the muscle fibers it stimulates.
What are small motor units?
What are small motor units?
Muscles with one neuron innervating a few muscle fibers, allowing for precise movements.
What is recruitment (or multiple motor unit summation)?
What is recruitment (or multiple motor unit summation)?
Activating more motor units to increase muscle tension and generate greater force.
What is muscle tone?
What is muscle tone?
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What is a muscle twitch?
What is a muscle twitch?
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What is summation?
What is summation?
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What is Tetanus?
What is Tetanus?
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Study Notes
- Motor units consist of a nerve cell (nerve fiber) and all the muscle fibers that it stimulates.
- Tiny motor units in areas like the eyes and fingers allow for fine motor control.
- Small motor units can have one neuron innervating as few as 1-3 muscle fibers.
- Large motor units in the thighs and gluteal muscles consist of 1 neuron stimulating up to 2000 muscle fibers.
- Thighs do not have fine motor control, but they can generate great power due to their large motor units.
- Lifting heavy objects requires the activation of more motor units, which engages more muscle fibers/cells.
Muscle Stimulation and Contraction
- A skeletal muscle contracts when its motor unit is stimulated.
- A single contraction is called a muscle twitch.
- A muscle twitch involves a single stimulus-contraction-relaxation sequence that occurs rapidly.
- A single muscle twitch cannot perform work; muscle cells require repeated stimulation in a process called summation.
- Repeated stimulation without full relaxation leads to increased tension, peaking during normal muscular contractions.
- Peak and sustained tension, or tetanus, is a state of maximal sustained contraction.
- Activating more motor units increases the amount of force produced, known as recruitment, or multiple motor unit summation.
- Motor units are activated on a rotating basis to reduce fatigue.
- Tone is a continuous, partial contraction of alternate muscle fibers, maintaining muscle firmness.
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