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Review - movement

3 important questions on Review - movement

Describe basic muscle anatomy.

- skeletal muscles are composed of many muscle fibers
- each muscle fiber is composed of many myofibrils
- myofibrils composed of overlapping strands of actin and myosin
- actin and myosin form repeating sarcomeres.
- myosin heads "row" against the actin filaments to contract the muscle by reducing the length of the sarcomere.
- types of muscle fibers

extrafusal- responsible for force exerted by contraction
intrafusal- stretch receptors, detect changes in muscle length.

- neuromuscular junction is the synapse between the terminal button of a motor neuron and the membrane of a muscle fiber.

acetylcholine is released and causes EPSP at motor endplate
depolarization of muscle fibers causes contraction

Describe a motor unit and motor endplates.

A motor unit is 1 alpha motor neuron, its axon, and associated extrafusal muscle fibers (fewer fibers = more precise control)
- motor endplate is where the terminal button of the motor neuron synapses.

Describe the function of different components of muscles, fibers, GTO.

- flexor muscles - contraction produces flexion- moving limb towards the body
- extensor muscles - extension is moving limb away from the body

- intrafusal muscle fibers

spindle afferent neurons - send sensory info to spinal cord
gamma motor neurons - send motor signals to muscle fibers

- golgi tendon organs - located at junction of muscle an tendon --> respond to increases in muscle tension, not length; regulates muscle tension, acts as a brake to prevent overly vigorous contraction.

The question on the page originate from the summary of the following study material:

Physiology of Behavior | 9780134080918 | Neil R Carlson

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