|
MEPP
End plate potentials (EPPs) are the voltages which cause depolarization of skeletal muscle fibers caused by neurotransmitters binding to the postsynaptic membrane in the neuromuscular junction. They are called "end plates" because the postsynaptic terminals of muscle fibers have a large, saucer-like appearance. When an action potential reaches the axon terminal of a motor neuron, vesicles carrying neurotransmitters (mostly acetylcholine) are Exocytosis, exocytosed and the contents are released into the neuromuscular junction. These neurotransmitters bind to receptors on the postsynaptic membrane and lead to its depolarization. In the absence of an action potential, acetylcholine vesicles spontaneously leak into the neuromuscular junction and cause very small depolarizations in the postsynaptic membrane. This small response (~0.4mV) is called a miniature end plate potential (MEPP) and is generated by one acetylcholine-containing vesicle. It represents the smallest possible depol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuromuscular Junction
A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. Muscles require innervation to function—and even just to maintain muscle tone, avoiding atrophy. In the neuromuscular system nerves from the central nervous system and the peripheral nervous system are linked and work together with muscles. Synaptic transmission at the neuromuscular junction begins when an action potential reaches the presynaptic terminal of a motor neuron, which activates voltage-gated calcium channels to allow calcium ions to enter the neuron. Calcium ions bind to sensor proteins (synaptotagmins) on synaptic vesicles, triggering vesicle fusion with the cell membrane and subsequent neurotransmitter release from the motor neuron into the synaptic cleft. In vertebrates, motor neurons release acetylcholine (ACh), a small molecule neurotransmitter, whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
