On arrival of an action potential at the nerve terminal, Ca channels open to cause influx. ![]() These proteins are essential for fusion and docking of SVs at active zones. The membrane of SVs has synaptotagmin and synaptobrevin proteins. The SVs are concentrated around the active zone. Each SV stores around 5000-10000 molecules of acetylcholine (ACh), the neurotransmitter at NMJ. A nerve terminal also has potassium channels on its membrane and contains mitochondria, endoplasmic reticulum, and synaptic vesicles (SVs). Active zones have a family of SNAP proteins (syntaxins and synaptosomal-associated protein 25) and rows of voltage-gated calcium (Ca) channels. ![]() The nerve terminal membrane has areas of membrane thickening called active zones. These nerve endings are called nerve terminals or terminal boutons. Nerve Terminal: A myelinated motor neuron, on reaching the target muscle, loses its myelin sheath to form a complex of 100-200 branching nerve endings. Physiological Anatomy of Neuromuscular Junctionįor convenience and understanding, the structure of NMJ can be divided into three main parts: a presynaptic part (nerve terminal), the postsynaptic part (motor endplate), and an area between the nerve terminal and motor endplate (synaptic cleft).
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