Muscles Lab Report

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Muscles (Grip strength)
In this week’s lab, we was doing an experiment on forearm, and its muscle fiber with nerves. The forearm is a part that between the primates’ elbow and wrist. Forearms contain connective tissue, nerve tissue and muscle tissue. In which, connective tissue is just radius and ulnar bones. However, there are a great deal of muscles and nerves in the forearm. When a nerve impulse transmission to synaptosomes induced depolarization, allows calcium ions to enter the cell membrane, the synaptic vesicles move forward and release acetylcholine (ACH). ACH combined with membrane receptors on the endplate cause electronic potentials, potassium and sodium ions exchanging start to spread both sides of muscle cell membrane to form the action potentials, and long with the cell membrane so that both sides of the terminal cistern will release Ca2+, Ca2+ and troponin binding to change tropomyosin, let actin exposed binding site to the cross bridge.
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One nerve cell can control lots of muscle fiber, they can form a motor unit. When we do muscle contraction, motor units are activated to send electron signal to muscles, then muscles can do contraction. According to the different physiological function, motor unit can be divided into 2 categories, kinetic motor unit and tonic motor unit. The high frequency of electron signal released when the motor unit of the muscle fiber is excited, the contraction force is strong, but is easy to fatigue, it is the fast fatigable motor unit. When the muscle fibers in the tonic motor unit are excited, the impulse frequency is low, but it can be released for a long time, it is slow oxidative unit. Basically, the more numbers of muscle fibers in a motor unit, it will be less flexible, and the force is large. On the other hand, fewer muscle fibers make motor unit become more flexible but less

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