Muscular System PDF Fall 24
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This document provides a comprehensive overview of the muscular system, covering various aspects such as its structure, function, and associated processes. The document includes diagrams and explanations of concepts like muscle attachments, connective tissues, and the sliding filament theory.
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Muscular System Chapter 10 Movement body parts substances stabilization posture protection and support elimination of materials heat generation Defining Characteristics Characteristics of Skeletal Muscle Excitability Conductivity Contractility Extensibi...
Muscular System Chapter 10 Movement body parts substances stabilization posture protection and support elimination of materials heat generation Defining Characteristics Characteristics of Skeletal Muscle Excitability Conductivity Contractility Extensibility Elasticity Naming Muscles Location Size Shape Action Number Actions Skeletal Muscle Attachments Tendon –muscle to bone, skin, or another muscle Aponeurosis – thin, flattened sheetlike tendon Attachments for axial muscles: Superior attachment (usually more moveable) Inferior attachment (usually less moveable) Attachments for appendicular muscles: Proximal attachment (usually less moveable) Distal attachment (usually more moveable) Body Musculature Organizational Patterns of Skeletal Muscle fibers Circular Parallel Convergent Pennate Unipennate Bipennate Multipennate Stabilized by connective tissues Epimysium Function: binds fascicles into “muscles” perimysium Surrounds _________________ Fasicle(s): bundles of muscle fibers endomysium Surrounds ______________ sheathes fibers Microanatomy of a muscle fiber Sarcomere: contractile unit of myofibril Thick = myosin Thin = actin Z line/disc: anchor actin Ends of sarcomere M- Line – anchors myosin I band – actin - lighter A Band - myosin – darker Sarcoplasmic reticulum – Ca++ storage Ca++ available for fast release Ca++ may also be available from the extracellular space (slower) – Terminal Cisternae – Ca++ reservoirs Is skeletal muscle voluntary or involuntary? What does it need to contract? Motor Unit – Innervation Motor unit: Neuron and the muscle fibers it innervates Number of fibers a neuron innervates varies Small motor unit = < 5 MFs Large motor units = >1000 MFs NMJ MN innervates muscle Synaptic knob Synaptic cleft Motor end plate Figure 10.9 Sliding Filament Theory Myosin crossbridges attach to binding site on actin pulls on actin releases moves to next binding site Figure 12.19 Events of an Action Potential
