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PowerPoint® Lecture Slides prepared by Barbara Heard, Atlantic Cape Community Ninth Edition College Human Anatomy & Physiology CHAPTER © Annie Leibovitz/Contact Press Images 9 © 2013 Pearson Education, Inc. An Introduction to Muscle Tissue • Muscle Tissue • 3 kinds: • Skeletal muscle tissue • Cardiac muscle tissue • Smooth muscle tissue © 2012 Pearson Education, Inc. Organization of Muscle • Muscles have three layers of connective tissues 1. Epimysium -“above” 2. Perimysium -“around” 3. Endomysium -“internal” © 2012 Pearson Education, Inc. Skeletal Muscle (organ) Epimysium Epimysium -Collagen layer -Separation from other tissues Tendon © 2012 Pearson Education, Inc. Fascicles Muscle Fascicle (bundle of fibers) Perimysium nucleus Tendon bundle of fibers = bundle of cells Perimysium © 2012 Pearson Education, Inc. surrounds individual muscle cells Muscle Fiber (cell) Capillary Axon of neuron Where do all these connections go? © 2012 Pearson Education, Inc. Endomysium Organization of Muscle • Endo- + peri- + epimysium leave together • at ends of muscles • attaches muscle to bone • If in bundle: tendon • If in flat-sheet : aponeurosis • So, how does muscle form? What’s going on at the cellular level? © 2012 Pearson Education, Inc. Myoblasts Myoblasts fuse Myosatellite cell? Immature myotube Myosatellite cell Nuclei Up to 30 cm in length Mature muscle fiber © 2012 Pearson Education, Inc. 11.8 in Figure 10-2b The Formation of a Multinucleate Skeletal Muscle Fiber Muscle fiber LM × 612 Sarcolemma © 2012 Pearson Education, Inc. Nuclei A diagrammatic view and a micrograph of one muscle fiber. Characteristics of Skeletal Muscle Fibers • The sarcolemma • cell membrane of muscle cell • Surrounds the sarcoplasm (cytoplasm) • when charge outside/inside the sarcolemma changes à contraction © 2012 Pearson Education, Inc. Characteristics of Skeletal Muscle Fibers • Muscle cells are made up of: • Myofibrils • Lengthwise subdivisions • within muscle cell © 2012 Pearson Education, Inc. Myofibril Sarcolemma Sarcoplasm © 2012 Pearson Education, Inc. MUSCLE FIBER Myofibrils have myofilaments indside -think contraction Myofibril Thin filament Thick filament OK….so these contract, but what makes them contract? © 2012 Pearson Education, Inc. Terminal cisterna Sarcoplasmic T tubules reticulum Smooth ER Stores & pumps Ca2+ © 2012 Pearson Education, Inc. Allow contraction Structural Components of a Sarcomere • Sarcomeres • contractile units of muscle • Form visible patterns within myofibrils © 2012 Pearson Education, Inc. Sarcomere Thin filament © 2012 Pearson Education, Inc. Thick filament Sarcomere Z line © 2012 Pearson Education, Inc. Zone of overlap Z line Thin Filament+ Titin Actin Z line © 2012 Pearson Education, Inc. Thick Filament Titin M line Myosin head Myosin tail © 2012 Pearson Education, Inc. Hinge Contraction is the result of a mechanical interaction of (two things): A. Active site Ca2+ Troponin Active site Tropomyosin Actin (balls) © 2012 Pearson Education, Inc. Thin Filament Contraction is the result of a mechanical interaction of (two things): B. Myosin head Titin -interacts with Actin filaments -forms crossbridges M line Myosin head Myosin tail ATPàHinge pivots © 2012 Pearson Education, Inc. I band Z line © 2012 Pearson Education, Inc. A band Z line I band A band Z line Z line Z-lines move closer Sliding Filament © 2012 Pearson Education, Inc. Theory Neural control • Neural stimulation of sarcolemma • Causes excitation–contraction coupling © 2012 Pearson Education, Inc. 1 Skeletal Muscle Innervation -Need contraction? Motor neuron Path of electrical impulse (action potential) Axon Neuromuscular junction Synaptic terminal SEE BELOW Sarcoplasmic reticulum Motor end plate Myofibril © 2012 Pearson Education, Inc. Motor end plate -NMJ/Motor-End Pl.: nervous + skeletal connection -How does this happen? Background Setup: Neuron – Muscle Connection Vesicles AChE © 2012 Pearson Education, Inc. ACh Arriving Signal Signal to release! © 2012 Pearson Education, Inc. AP @ synaptic terminal Permeability changes The synaptic cleft. ACh © 2012 Pearson Education, Inc. Let me In! ACh receptor site © 2012 Pearson Education, Inc. Action Potential b/c Na ions rushed in © 2012 Pearson Education, Inc. Components of the Neuromuscular Junction • Action potential reaches a Sarcoplasmci Retic. • Ca2+ Released • Tropomyosin moves out of the way • contraction! • Is the story over? • nope © 2012 Pearson Education, Inc. AChE If no AChE? AChE © 2012 Pearson Education, Inc. Serin gas
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