Muscle Fibers and Neurons

Match the following:

• Motor Unit

• motor neuron and all of the muscle fibers it connects to

• Synapse

• chemical messengers that allow neurons to communicate with each other

• neurotransmitter

• a specialized connection between neurons or between a neuron and an effector cell (muscle fibers)

• Neuromuscular Junction

• • specialized nerve cells in the brain and spinal cord that control voluntary and involuntary movements

• Motor Neurons

• where a motor neuron meets a muscle fiber

Place the steps in the correct order to describe how a motor neuron triggers contraction in a muscle fiber.

• Action potential travels through muscle fiber and calcium is released, triggering the sliding-filament mechanism

• Acetylcholine binds to ligand-gated protein channel

• Action potential travels through neuron

• Action potential reaches axon (end) of neuron and acetylcholine is released

• Protein channel opens and sodium ions move into muscle fiber making it more positive (depolarization)