Muscle Anatomy - Human Physiology - Lecture Slides, Slides of Human Biology

Download Muscle Anatomy - Human Physiology - Lecture Slides and more Slides Human Biology in PDF only on Docsity! Chapter 12: Muscles Review muscle anatomy (esp. microanatomy of skeletal muscle) Docsity.com Terminology:  sarcolemma  t-tubules  sarcoplasmic reticulum  myofibers, myofibrils, myofilaments  sarcomere Docsity.com T-tubule brings action Thin filament potentials into interior of muscle fiber. Sarcolemma Thick filament Triad Sarcoplasmic reticulum Terminal stores Ca**. cisterna Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Myofibrils = Contractile Organelles of Myofiber  Actin  Myosin  Tropomyosin  Troponin  Titin  Nebulin Contractile Regulatory Accessory Contain 6 types of protein: Fig 12-3 c-f Docsity.com L nnn Supe bed voy eater Cohiba TT pe ws 5 Z disk Thin filament Titin ee oe Troponi Nebui oa roponin lin Tropomyosin G-actin molecule Docsity.com Rigor State myosin affinity changes due to ATP binding ATP ADP + Pi  Tight binding between G-actin and myosin  No nucleotide bound ATP binds  dissociation The Molecular Basis of Contraction Compare to Fig 12-9 Docsity.com Myosin head acts as ATPase Released energy changes angle between head & long axis of myosin Rotation and weak binding to new G-actin Relaxed muscle state when sufficient ATP Docsity.com Power stroke begins as Pi released ADP released Tight binding to actin Myosin crossbridge movement pushes actin Docsity.com Initiation of Contraction Excitation-Contraction Coupling explains how you get from AP in axon to contraction in sarcomere ACh released from somatic motor neuron at the Motor End Plate AP in sarcolemma and T-Tubules Ca2+ release from sarcoplasmic reticulum Ca2+ binds to troponin Docsity.com Nicotinic cholinergic receptors on motor end plate = Na+ /K+ channels  Net Na+ entry creates EPSP  AP to T-tubules  DHP (dihydropyridine) receptors in T- tubules sense depolarization Details of E/C Coupling Fig 12-11 Docsity.com Ttubule brings action Thin filament potentials into interior of muscle fiber. Sarcolemma Thick filament Triad Sarcoplasmic reticulum Terminal stores Ca”, cisterna ( _—— Axon terminal of / “somatic motor neuron Muscle fiber 4 . a SIS I Action potential ——— ic Motor “end plate =] jropamyosin i ropenin Myosin thick filament