8 - Contraction of Motor units
Terms
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- motor units
- What are the groups of muscle cells called, within a muscle, that are innervated by one motor neuron and contracted together and stimulated by that motor neuron?
- The size & # of motor units being stimulated
- What important factors determine the strength of contraction of a muscle
- motor unit
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a motor nueron
& all of the muscle cells it stimulates - neuromuscular junction
- What is the junction between the branch of an neuron and a muscle cell called?
- all of the muscle cells which are stimulated by that one neuron will contract.
- When a motor neuron fires, how many muscle cells are stimulated?
- The more motor units there are, the stronger the contraction will be.
- What is the relationship between the strength of the muscle contraction and the number of motor units which are stimulated?
- recruitment
- The stimulation of additional motor units to increase strength of a contraction.
- it generates precise movements
- What is the general function of motor units that contain only a few muscle cells?
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1. # of motor units firing
2. # of cells per motor unit - What two factors effect the strength and degree of muscle movement?
- Have large motor units in which a single neuron is connected to a large # of muscle cells
- Describe the motor units in large muscles which exhibit gross movements.
- The eye has more complex movements (small, but important) compared to muscle movement in the thigh, which is gross movement.
- What did the virtual professor mean when she said "small precise muscles that cause fine movements, like those of the eye, have a huge number of motor fibers controlling them, comparatively speaking.?"
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a. small
b. large
c. large
d. small -
Tell if the following muscles would have small or large motor units:
a. muscles of the fingers
b. biceps brachii muscle
c. gastrocnemius muscle
d. muscles of the throat involved in speech - interneuron
- A neuron within the brain or spinal cord that lies between sensory and motor neurons. Also called an association neuron.
- muscle tone
- The nearly constant state of low-level tension and resistance to stretch in a muscle.
- activities of the spinal cord & result in firmness of the muscle
- What causes muscle tone?
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They become flaccid & briefly contract by nerve impulses.
they stretch by the weight of the muscle. - What happens to a muscle if all the motor neurons to that muscle are cut?