figure 10.17 the arrangement of motor units in a skeletal muscle
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Figure 10.17 The Arrangement of Motor Units in a Skeletal Muscle. Figure 10.17. Tension production by skeletal muscles. Internal tension generated inside contracting muscle fibers External tension generated in extracellular fibers. Figure 10.16 Internal and External Tension. Figure 10.16. - PowerPoint PPT PresentationTRANSCRIPT
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Figure 10.17
Figure 10.17 The Arrangement of Motor Units in a Skeletal Muscle
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• Internal tension generated inside contracting muscle fibers
• External tension generated in extracellular fibers
Tension production by skeletal muscles
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Figure 10.16 Internal and External Tension
Figure 10.16
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• Motor units– All the muscle fibers innervated by one neuron– Precise control of movement determined by number
and size of motor unit
• Muscle tone– Stabilizes bones and joints
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Figure 10.17
Figure 10.17 The Arrangement of Motor Units in a Skeletal Muscle
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• Isometric– Tension rises, length of muscle remains constant
• Isotonic• Tension rises, length of muscle changes
• Resistance and speed of contraction inversely related
• Return to resting lengths due to elastic components, contraction of opposing muscle groups, gravity
Contractions
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Figure 10.18 Isotonic and Isometric Contractions
Figure 10.18
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Figure 10.19
Figure 10.19 Resistance and Speed of Contraction
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• Creatine phosphate (CP) releases stored energy to convert ADP to ATP– CP made creatine with excess ATPs
– Returns energy to ATP via enzyme creatine phosphokinase (CPK); excess in blood with muscle damage
• Aerobic metabolism (req. O2) provides most ATP needed for contraction
• Glycolysis in cytoplasm; oxidative phosphorylation in mitochondria
• At peak activity, anaerobic glycolysis needed to generate ATP
• Fermentation- lactate from pyruvate; temporarily maintains glycolysis without O2; far less ATP produced
Muscle Contraction requires large amounts of E
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Figure 10.20 Muscle Metabolism
Figure 10.20
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Figure 10.20 Muscle Metabolism
Figure 10.20
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• Energy production and use patterns mirror muscle activity
• Fatigued muscle no longer contracts– Build up of lactic acid– Exhaustion of energy resources
• lack of ATP, CP, pH drop (lactate)
Energy use and level of muscular activity