lab_2 - Experiment 2: Skeletal Muscle 3 kinds of muscle:...

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Experiment 2: Skeletal Muscle 3 kinds of muscle: (1) skeletal (2) cardiac and (3) smooth Muscle fiber : Basic unit of contraction. It is multinucleated (10-100 uM) and contains myofibrils. Contractile unit of myofibril : actin and myosin filaments Muscle innervated by nerves called motor neurons. One neuron can innervate several muscle fibers butone muscle fiber is only innervated by a single muscle fiber Motor unit : Motor neuron + muscle fibers it innervates. Excitation-Contraction coupling: depolarization of motor neuron release of neurotransmitter (NT), mainly ACh NT binds to receptors nicotinic ACh receptors opens ligand gated Na + channels depolarization muscle fiber Action potential (AP travels down T-tubule system to sarcoplasmic reticulum (SR) SR releases Ca 2+ Ca 2+ binds troponin-tropomyosin complex conformational change uncovers myosin binding site in actin contraction(isometric vs isotonic) Isometric same length develops tension Isotonic same tension shortens the muscle
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This note was uploaded on 06/07/2009 for the course NPB 101L taught by Professor Goldberg during the Spring '08 term at UC Davis.

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