End-plate potential: Difference between revisions

'''End plate potentials''' ('''EPPs''') are the depolarizations 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 depolarizationsdepoljoarizations in the postsynaptic membrane. This small response (~0.4mV)<ref>{{Cite book|title=Medical Physiology|last=Boron|first=W.|last2=Boulpaep|first2=E.|publisher=Saunders, Elsevier inc.|year=2012|isbn=978-0-8089-2449-4|location=Philadelphia, PA|pages=224}}</ref> is called a miniature end plate potential (MEPP) and is generated by one acetylcholine-containing vesicle. It represents the smallest possible depolarization which can be induced in a muscle.