PNB 2274 Lecture 10: Muscle and Neuromuscular Junction — PNB Lecture 10 Notes
12 Apr 2018
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Document Summary
Muscle anatomy has 4 fairly unique characteristics: excitability from outside stimuli causes action potential in skeletal muscle, and then muscle contracts. 3 elasticity, stretched muscle returns to original length. Types are skeletal muscle (700ish, moves skeleton around joints), cardiac muscle, and smooth muscle. Muscle organized in bundles wrapped by ct, inside those bundles there are fascicles (bundles of muscle fibers/cells), a myofibril is the cytoskeletal protein fibers inside a cell that are arranged in almost crystalline structure. Motor unit consists of 1 neuron stimulating all of the individual muscle fibers the nerve innervates, how ms structurally organized. A motor axon doesn"t innervate every muscle fiber in a muscle, innervates from a few to maybe a few dozen, one muscle can have many motor units. Either a motor unit totally contracts, or not. Henneman"s size principle- as force increases, more and larger motor units recruited to generate larger force. Just know diff types of motor units exist.
