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In neurons, action potentials play a central role in cell–cell communication by providing for—or with regard to saltatory conduction, assisting—the propagation of signals along the neuron's axon toward synaptic boutons situated at the ends of an axon; these signals can then connect with other neurons at synapses, or to motor cells or ...
A single motor neuron may innervate many muscle fibres and a muscle fibre can undergo many action potentials in the time taken for a single muscle twitch. As a result, if an action potential arrives before a twitch has completed, the twitches can superimpose on one another, either through summation or a tetanic contraction.
In biology, a motor unit is made up of a motor neuron and all of the skeletal muscle fibers innervated by the neuron's axon terminals, including the neuromuscular junctions between the neuron and the fibres. [1] Groups of motor units often work together as a motor pool to coordinate the contractions of a single muscle. The concept was proposed ...
When the motor nerve is stimulated there is a delay of only 0.5 to 0.8 msec between the arrival of the nerve impulse in the motor nerve terminals and the first response of the endplate [7] The arrival of the motor nerve action potential at the presynaptic neuron terminal opens voltage-dependent calcium channels, and Ca 2+ ions flow from the ...
The neuromuscular junction is the synapse that is formed between an alpha motor neuron (α-MN) and the skeletal muscle fiber. In order for a muscle to contract, an action potential is first propagated down a nerve until it reaches the axon terminal of the motor neuron.
The signals can only continue along the neuron to cause an action potential further down if they are strong enough to make it past the cell's membrane resistance and capacitance. For example, a neuron with a large diameter has more ionic channels in its membrane than a smaller cell, resulting in a lower resistance to the flow of ionic current.
Typical action potential frequency is between 4 and 12 Hz. An electrical stimulation can artificially elicit this action potential by changing the electric potential across a nerve cell membrane (this also includes the nerve axon) by inducing electrical charge in the immediate vicinity of the outer membrane of the cell.
Activity in the motor neuron causes contraction in all of the innervated muscle fibers so that they function as a unit. Increasing action potential frequency (spike rate) in the motor neuron increases the muscle fiber contraction force, up to the maximal force. [6] [7] The maximal force depends on the contractile properties of the muscle fibers.