lecture6-11

Lecture6-11 - spinal cord motor neuron motor neuron fires action potential spreads through muscle cell contraction results from shortening of

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Unformatted text preview: spinal cord motor neuron motor neuron fires, action potential spreads through muscle cell contraction results from shortening of muscle fiber skeletal muscle cell (fiber) •very large cells (2-3 cm long) •polynucleated •mature muscle fiber forms by fusion of multiple myoblasts Questions: 1. How is depolarization of muscle cell linked to contraction of cell? 2. What is the molecular basis of contraction? •usually connected to bones via tendons • striated appearance lecture 6 skeletal muscle the workings of the skeletal muscle involves the muscle itself and the somatic nervous system brain one muscle fber (cell) • muscle fber : (same a skeletal muscle cell). It is composed oF multiple myofbrils. They usually extend the length oF the muscle fber myofbril • myofbril : bundle oF contractile proteins. Muscle contracts when myofbrils shorten. These are the Force generating parts oF the muscle cell •each myofbril has repeating units called sarcomeres. Under the microscope the myofbrils have a banded appearance - the lines are given names (H, M...) •the most important line to know is the Z line (or band). When a muscle contracts the distance between the Z lines decreases • myofbrils must be anchored to each other and to the plasma membrane to get muscle fber to contract as a single unit. z line z line •the sarcomere is the unit of contraction •thick Flaments - bundles of the protein myosin . Polarity of the bundles reversed at M line •thin Flaments -- helical bundles of the protein actin • actin Flaments attached to the Z line (actually disk) M line The sarcomere contains a number of other accessory proteins, among them are:...
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This note was uploaded on 02/14/2011 for the course MCDB 111 taught by Professor Smith during the Spring '11 term at UCSB.

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Lecture6-11 - spinal cord motor neuron motor neuron fires action potential spreads through muscle cell contraction results from shortening of

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