Characteristics of Muscle Irritability Ability to respond to stimulation Contractility Ability to shorten when it receives sufficient stimulation Unique to muscle tissue Extensibility Ability to stretch/lengthen beyond resting length Protective mechanism Elasticity Ability to return to resting length after being stretched Protective mechanism
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Characteristics of Muscle Irritability Ability to respond to stimulation Contractility Ability to shorten when it receives sufficient stimulation Unique.
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Characteristics of Muscle
Irritability Ability to respond to stimulation
Contractility Ability to shorten when it receives sufficient stimulation Unique to muscle tissue
Extensibility Ability to stretch/lengthen beyond resting length Protective mechanism
Elasticity Ability to return to resting length after being stretched Protective mechanism
Groups of Muscles
Muscles typically act in unison – not individually Fascia
Sheet of fibrous tissue Compartmentalizes groups of muscles
Individual Muscle Organization
Belly Thick central portion
Epimysium Outside covering of a
muscle Fascicles
Bundles of muscle fibers Perimysium
Dense connective sheath covering a fascicle
Fibers Cells of a skeletal muscle
Individual Muscle Organization (cont.)
Endomysium Very fine sheath covering individual fibers
Sarcolemma Thin plasma membrane branching into muscle
Myofibrils Rod-like strands of contractile filaments Many sarcomeres in series
Sarcoplasma Cytoplasm of muscle cell
Sarcoplasmic reticulum Specialized endoplasmic reticulum of muscle cells
Individual Muscle Organization (cont.)
T-tubules Extension of sarcolemma that protrudes into muscle
cell Also called, transverse tubule
Myosin Thick, dark filament
Actin Thin, light filament
Sarcomere Unit of myosin and actin Contractile unit of muscle
Fiber Organization
Fusiform Parallel fibers and fascicles High speed of contract, force production ACS = PCS