BSc Unit 3 Lecture 1 PDF
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This document is a lecture on muscle tissue structure and characteristics. It includes learning outcomes, terminology, and figures. It covers sarcoplasm, sarcoplasmic reticulum, myofibrils, and protein filaments.
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10/27/24 1 Muscle Tissue I 2 Learning Outcomes 3 LO1: Muscle tissue Striated Skeletal Cardiac Smooth 4 5 LO1: Muscle cell characteristics 6 Structure of Muscle Cells Myocyte (muscle cell) terminology:...
10/27/24 1 Muscle Tissue I 2 Learning Outcomes 3 LO1: Muscle tissue Striated Skeletal Cardiac Smooth 4 5 LO1: Muscle cell characteristics 6 Structure of Muscle Cells Myocyte (muscle cell) terminology: Sarcoplasm - myocyte’s cytoplasm Sarcolemma - myocyte’s plasma membrane Sarcoplasmic reticulum (SR) - modified endoplasmic reticulum: – Forms web-like network surrounding myofibrils – Varies in structure in three types of muscle tissue (discussed later) 7 LO1: Muscle cells 8 Learning Outcomes 9 LO2: Skeletal muscle organization 10 Learning Outcomes 11 LO3:The Skeletal muscle fiber 12 Structure of the Skeletal Muscle Fiber Figure 10.4 Structure of a skeletal muscle fiber. 13 14 1 15 12 Figure 10.4 Structure of a skeletal muscle fiber. 13 Structure of the Skeletal Muscle Fiber 14 LO3: Sarcoplasmic reticulum 15 Structure of the Myofibril Three types of myofilaments (Figure 10.5): Thick filaments - bundles of contractile protein myosin Thin filaments - proteins actin, tropomyosin, and troponin Elastic filaments - single massive, spring-like structural protein (titin); stabilizes myofibril structure; resists excessive stretching 16 LO3: Myofibrils 17 Learning Outcomes 18 Myofilament Arrangement and the Sarcomere Light and dark bands with specific regions (Figures 10.6, 10.7): I band (“i” in light, mnemonic) - only thin filaments Z disc - in middle of I band; composed of structural proteins that: – Anchor thin filaments in place and to one another – Serve as attachment points for elastic filaments – Attach myofibrils to one another across entire diameter of muscle fiber 19 LO4: Protein myofilament arrangement Sarcomere Functional contractile unit Occurs between 2 Z-discs Sarcomere 20 21 22 23 Sarcomere 20 LO4: Sliding filament mechanism of contraction 21 22 Learning Outcomes 23 LO5: Membrane potential 24 LO5: Sodium potassium pumps help generate resting membrane potentials 25