- All-or-None Law of Skeletal Muscle Contraction: An individual muscle fiber contracts with equal force in response to each action potential.
- Maximal Stimulus: A stimulus which is strong enough to create action potentials in all the motor neurons innervating a whole muscle.
- Muscle Tone: The state of partial contraction in a muscle, even when the muscle is not being used.
- Neuron: The functional unit of the nervous system, a nerve cell.
- Neurotransmitter: A chemical released by a neuron. This chemical travels across the synaptic cleft, allowing the neuron to communicate with another cell.
- One motor neuron and all the muscle fibers it innervates.: Motor Unit
- Sarcomere: The repeating unit of a myofibril.
- Submaximal Stimuli: Stimuli of increasing strength that create more action potentials along more neurons.
- Subthreshold Stimulus: A stimulus too small to create an action potential in a neuron.
- Synapse: The interface between a nerve cell and another cell.
- Threshold Stimulus: A stimulus strong enough to create one action potential in a neuron.