BIOL273 Study Guide - Golgi Tendon Organ, Alpha Motor Neuron, Muscle Spindle
19 Nov 2013
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Document Summary
Only contract in response to somatic motor neurons. Sarcoplasmic reticulum contain terminal cisternae, which release ca2+ ions. 1 t-tubule and the 2 terminal cisternaes on each side is called a triad. Lumen of t-tubules contain extracellular fluid. (t-tubule = transverse tubule) t-tubules move action potentials from outside of cell to inside of cell. Myofibrils are the structures that contract in muscle. Myosin is the motor protein that creates movement in the muscle. 250 myosin molecules join to create the thick filament. Under the light microscope, repetitions of thick and thin filaments create the repeating pattern of light and dark bands. Z discs- 2 of them in 1 sarcomere. I band- lightest colour bands of the sarcomere, and represent a region that consists of only thin filaments. A band- darkest band of the sarcomere, and includes the entire length of the thick filaments. H zone- middle part of a band, is lighter than a band because it contains only thick filaments.
