Medical Sciences 3999A/B/Y Lecture Notes - Lecture 22: Myocyte, Cardiac Muscle, Intermediate Filament
16 Feb 2020
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Document Summary
Skeletal fibres innervated by large myelinated nerve fibres from large motor neurons (extending from the anterior horn of the spinal cord; mev) Each nerve fibre stimulates several hundred skeletal muscle fibres. Each nerve ending makes nmj with muscle fibre near its midpoint. 98% of the muscle have only one junction per muscle fibre. Neuromuscular junction (nmj): specialized synapse between a motor neuron and a muscle fibre; occurs at the motor end plate on a muscle fibre (one per fibre) Covered by schwann cells --> insulation from surrounding fluids. Perisynaptic schwann cells or terminal schwann cells (a. k. a. Teloglia) are neuroglia found at nmjs; functions in: Neuromuscular transmission: via ach and modulation by ache. Acetylcholine: synthesized in cytoplasm terminal and absorbed into small synaptic vesicles (~300,000 or more in single endplate) Acetylcholinesterase: attached to spongy layer fine ct in synaptic space. Synaptic trough: invagination in motor endplate membrane; synaptic clefts in the bottom.
