PSYCH261 Chapter Notes - Chapter 1: Extrafusal Muscle Fiber, Lateral Corticospinal Tract, Gamma Motor Neuron
6 Sep 2017
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Note: there is a common misconception that people (cid:498)flex their muscles(cid:499) but this is not true. Muscle fiber: a fiber consists of a bundle of myofibrils, each consists of overlapping actin/myosin strands, myosin cross bridges are where the actual contraction occurs, striations are where actin/myosin filaments overlap. Motor unit: motor neuron + its muscle fibers. Myofibril: overlapping strands of actin + myosin responsible for contraction. Motor endplate: postsynaptic membrane of a neuromuscular junction. Endplate potential: postsynaptic potential that occurs in the motor endplate in response to release of ach by tb. Golgi tendon organ: receptor organ at junction of tendon and muscle that is sensitive to touch. Gamma motor system: when gamma motor neurons are active they become shorter and more sensitive to changes in muscle length, when efferent axon is completely silent, spindle is relaxed + extended, increase firing rate and spindle gets shorter.
