Correct option is D
The correct answer is Miniature endplate potential (MEPP). In skeletal muscle cells, when a single quanta of acetylcholine is released from the motor nerve terminals, it generates a miniature endplate potential. This is a small, spontaneous electrical change that occurs at the motor endplate and is a result of the release of acetylcholine from a single synaptic vesicle. These MEPPs are subthreshold events and do not trigger a muscle contraction unless multiple MEPPs sum together to produce a larger potential (endplate potential) that reaches the threshold for an action potential.
Information Booster:
- Miniature endplate potentials (MEPPs) are small, localized changes in the membrane potential of the muscle fiber that result from the release of acetylcholine from individual vesicles (quantum release). MEPPs are important because they reflect the basic unit of neurotransmitter release at the neuromuscular junction. Although they are too small to cause a muscle contraction by themselves, they are essential for understanding how neurotransmitter release works at the synapse.
- These miniature potentials serve as the basis for the much larger endplate potential (EPP), which is generated when multiple quanta of acetylcholine are released and cause a significant depolarization, ultimately leading to muscle contraction.
Additional Information:
- Inhibitory post-synaptic potential: This is a type of synaptic potential that results from the inhibitory neurotransmitters like GABA or glycine at inhibitory synapses, not acetylcholine at the neuromuscular junction.
- Inhibitory junction potential: This term is related to the inhibitory effects at synapses involving inhibitory neurotransmitters but does not apply to the neuromuscular junction, where acetylcholine acts as the excitatory neurotransmitter.
- Endplate potential (EPP): This potential is a larger depolarization at the neuromuscular junction that occurs when multiple acetylcholine vesicles release their contents simultaneously, leading to an action potential and muscle contraction. It is a sum of several MEPPs, not generated by a single quantum.
