Brunel University London - Introduction to Medical Sciences 1 - Sarcomeres and Sliding Filament Theory Part 1 PDF

Introduction to Medical Sciences 1 Cell Signalling and Movement Sarcomeres and Sliding Filament Theory Part 1 Copyright © Brunel University London v.3 2024. All rights reserved. Cell Signalling and Movement Dr Julianna Gal Version 3 2024 Copyrig...

Introduction to Medical Sciences 1 Cell Signalling and Movement Sarcomeres and Sliding Filament Theory Part 1 Copyright © Brunel University London v.3 2024. All rights reserved. Cell Signalling and Movement Dr Julianna Gal Version 3 2024 Copyright © Brunel University London v.3 2024. All rights reserved. Cell Signalling and Movement Sarcomeres and Sliding Filament Theory Part 1 Copyright © Brunel University London v.3 2024. All rights reserved. Sarcomeres and Sliding Filament Theory Part 1: Skeletal muscle organisation and structure of sarcomeres Part 2: Skeletal muscle contraction and the sliding filament theory Part 3: Control of skeletal muscle force and role of calcium Copyright © Brunel University London v.3 2024. All rights reserved. Sarcomeres and Sliding Filament Theory Part 1: Skeletal muscle organisation and structure of sarcomeres Overview Anatomic organisation of skeletal muscle Fine ultrastructure of skeletal muscle Focus on the sarcomere, key biomolecules and their organisation Copyright © Brunel University London v.3 2024. All rights reserved.  Skeletal muscles come in a wide variety of shapes and sizes Iliopsoas Tensor fasciae latae Adductor longus Sartorius Biceps brachii- Biceps brachia- Latissimus dorsi short head long head Vastus medialis Copyright © Brunel University London v.3 2024. All rights reserved. All skeletal muscles have: Tendon of origin Muscle belly Tendon of insertion Skeletal muscles typically connect one bone to another, crossing at least one joint Muscle belly is the site of active force production When stimulated by central nervous system, muscle belly generates contractile or pulling-type force Contractile force pulls equally on tendon of insertion and tendon of origin What we see as the outcome of a skeletal muscle contraction depends upon the NET effect of all forces at each end of the muscle How does skeletal muscle actively generate force? Copyright © Brunel University London v.3 2024. All rights reserved. Organisation of skeletal muscle Copyright © Brunel University London v.3 2024. All rights reserved.  Scanning electron micrograph showing the tiny collagen fibres of the endomysium that bind skeletal muscle cells together (x 200) Copyright © Brunel University London v.3 2024. All rights reserved. Active force production occurs within the muscle cell Muscle cells (muscle fibres) are packed with: Myofibrils (force) Nuclei (repair, adaptation) Mitochondria (energy) How is the muscle cell organised to produce force? Copyright © Brunel University London v.3 2024. All rights reserved.  Light micrograph of part of skeletal muscle fibre Cross striation pattern is clear. Elongated nuclei are located in the peripheral areas Electron of cell. 1200 x micrograph of part of skeletal A A-band muscle I I-band Mi mitochondrion fibre N nucleus Z Z-line Dark and light bands are arranged in series along length of muscle fibre and show lateral registration with adjacent myofibrils. 3000 x Copyright © Brunel University London v.3 2024. All rights reserved. Electron micrograph of a relaxed sarcomere in longitudinal section 14,000 x Copyright © Brunel University London v.3 2024. All rights reserved.  Microscopy and myosin biochemistry give (contractile) evidence for a complex arrangement of proteins within each sarcomere actin, troponin, tropomyosin (regulatory) Copyright © Brunel University London v.3 2024. All rights reserved. Proteins which play a supportive role within skeletal muscle, e.g., nebulin and titin Copyright © Brunel University London v.3 2024. All rights reserved. Myosin heads forming cross bridges that generate muscular contractile force. Part of a sarcomere is seen in a transmission electron micrograph (277,000 X) Copyright © Brunel University London v.3 2024. All rights reserved. Summary Skeletal muscle contains significant amount of connective tissue: endomysium, perimysium and epimysium A skeletal muscle fibre IS a skeletal muscle cell The sarcomere is the site of force production Sarcomeres contain important molecules including myosin, actin, troponin, tropomyosin, nebulin and titin Copyright © Brunel University London v.3 2024. All rights reserved. Slide figures adapted from the following sources Slide 6 Gosling, J.A. Human Anatomy, Color Atlas and Textbook, Chapter 3, 71-133. Copyright 2017, Elsevier Ltd. Gosling, J.A. Human Anatomy, Color Atlas and Textbook, Chapter 6, 253-319. Copyright 2017, Elsevier Ltd. Gosling, J.A. Human Anatomy, Color Atlas and Textbook, Chapter 3, 71-133. Copyright 2017 Elsevier Ltd. Slide 7 Kierszenbaum, Abraham L. Histology and Cell Biology: An Introduction to Pathology, 7, 237-260. Copyright 2020, Elsevier, Inc. Copyright © Brunel University London v.3 2024. All rights reserved. Slide 8 Borg, T.K., and Caulfield J.B. Morphology of connective tissue in skeletal muscle. Tissue and Cell, Vol. 12, pp. 197-207. Copyright 1980, Longman Group, Ltd. Slide 10 Ovalle, William K. Netter's Essential Histology, 4, 77-107. Copyright 2021, Elsevier, Inc. Slide 11 Ovalle, William K. Netter's Essential Histology, 4, 77-107. Copyright 2021, Elsevier, Inc. Slide 12 Moczydlowski, Edward G. Boron and Boulapaep Concise Medical Physiology, Chapter 9, 100-114. Copyright 2021, Elsevier, Inc. Copyright © Brunel University London v.3 2024. All rights reserved. Slide 13 Kierszenbaum, Abraham L. Histology and Cell Biology: An Introduction to Pathology, 7, 237-260. Copyright 2020, Elsevier, Inc. Slide 14 Marieb, E.N. and Hoehn, K. Human Anatomy & Physiology Ninth Edition. p. 284. Copyright 2013, Pearson Education, Inc. Copyright © Brunel University London v.3 2024. All rights reserved. Dr Julianna Gal Copyright © Brunel University London v.3 2024. All rights reserved.