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Excitation–contraction coupling (ECC) occurs when depolarization of skeletal muscles (usually through neural innervation) results in a muscle action potential. This action potential spreads across the muscle's surface and into the muscle fiber's network of T-tubules , depolarizing the inner portion of the muscle fiber.
The slope of phase 0 on the action potential waveform (see figure 2) represents the maximum rate of voltage change of the cardiac action potential and is known as dV/dt max. In pacemaker cells (e.g. sinoatrial node cells ), however, the increase in membrane voltage is mainly due to activation of L-type calcium channels.
In muscle cells, for example, an action potential is the first step in the chain of events leading to contraction. In beta cells of the pancreas , they provoke release of insulin . [ a ] The temporal sequence of action potentials generated by a neuron is called its "spike train".
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 motor neuron then innervates the muscle fibers to contraction by causing an action potential on the postsynaptic membrane of the neuromuscular junction.
T-tubules are an important link in the chain from electrical excitation of a cell to its subsequent contraction (excitation-contraction coupling). When contraction of a muscle is needed, stimulation from a nerve or an adjacent muscle cell causes a characteristic flow of charged particles across the cell membrane known as an action potential. At ...
When necessary, the maximal number of motor units in a muscle can be recruited simultaneously, producing the maximum force of contraction for that muscle, but this cannot last for very long because of the energy requirements to sustain the contraction. To prevent complete muscle fatigue, motor units are generally not all simultaneously active ...
The endplate potential is thus responsible for setting up an action potential in the muscle fiber which triggers muscle contraction. The transmission from nerve to muscle is so rapid because each quantum of acetylcholine reaches the endplate in millimolar concentrations, high enough to combine with a receptor with a low affinity, which then ...
Cardiac excitation-contraction coupling (Cardiac EC coupling) describes the series of events, from the production of an electrical impulse (action potential) to the contraction of muscles in the heart. [1] This process is of vital importance as it allows for the heart to beat in a controlled manner, without the need for conscious input.