Lecture 13 Muscle Contraction

Lecture 13 Muscle Contraction - IPHY 3060 Lecture 13 Muscle...

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Unformatted text preview: IPHY 3060 Lecture 13: Muscle Contraction Important Point from Last Time: • Cells contain a cytoskeleton that provides structure and assists in cell movement Muscle Cells: Cells specialized to convert chemical energy into mechanical force in order to produce movement of bodily structures Motor Proteins: Proteins which work with cytoskeletal proteins to convert chemical energy into mechanical force 3 Types of Muscle Cells: • Skeletal muscle cells • Cardiac muscle cells • Smooth muscle cells Functions of the Different Types of Muscle Cells: • Skeletal muscle cells—voluntary movement of limbs and joints • Cardiac muscle cells—beating of the heart • Smooth muscle cells—regulate flow through body tubes—blood flow, air flow, digestion Skeletal muscle cells are long, cylindrical cells with a very organized cytoskeleton tendo ns Muscle Structure Musc le Bundle of Muscle Fibers Myofib rils Musc le Fiber Nucle us Single myofibr il Cardiac muscle cells are smaller but also have an organized cytoskeleton Smooth muscle cells form sheets surrounding body cavities and have a much less organized cytoskeleton Skeletal Muscle Contraction Movement of limbs is produced by skeletal muscle contraction Relaxed Muscle Muscle contraction Contracted Muscle Arm Relaxed Muscle Muscle contraction Contracted Muscle Arm Muscle Contraction The Sarcomere Sarcomere—a highly specialized cytoskeletal structure found in muscle cells Sarcomeres consist of overlapping thin filaments and thick filaments Thin filaments consist of actin filaments, troponin, and tropomyosin Thick filaments consist of myosin molecules The sliding filament model—thick filaments pull the thin filaments toward the center of the sarcomere Muscle Contraction and Myosin Myosin: Myosin: The motor protein responsible for producing muscle contraction Myosin consists of six subunits: • Two myosin heavy chains • Four myosin light chains Two Myosin Heavy Chains Functions of the Regions of the MyHC Molecule • Head region—binds to and hydrolyzes ATP, binds to actin filaments • Neck region—flexible part that actually moves, also binds light chains which regulate myosin function • Tail region—binds together to form thick filaments Head Neck Tail The Myosin Cross-Bridge Cycle and Muscle Contraction Key Point: Myosin heads or cross-bridges bind to the actin filament and pull them towards the center of the sarcomere Cross Bridge Cycle Cross Bridge Cycle...
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This note was uploaded on 08/11/2010 for the course IPHY 3060 taught by Professor Allen,davi during the Fall '09 term at Colorado.

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Lecture 13 Muscle Contraction - IPHY 3060 Lecture 13 Muscle...

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