Chapter 10, part 2
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Anatomy & Physiology SIXTH EDITION
Chapter 10, part 2 Muscle Tissue
PowerPoint® Lecture Slide Presentation prepared by
Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Frederic H. Martini
Fundamentals of
SECTION 10-3 The Contraction of Skeletal Muscle
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Tension
• Created when muscles contract • Series of steps that begin with excitation at the neuromuscular junction • Calcium release • Thick/thin filament interaction • Muscle fiber contraction • Tension
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Figure 10.9 An Overview of the Process of Skeletal Muscle
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Figure 10.9
Control of skeletal muscle activity occurs at the neuromuscular junction
• Action potential arrives at synaptic terminal • ACh released into synaptic cleft
• ACh binds to receptors on post-synaptic neuron • Action potential in sarcolemma
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Figure 10.10 Skeletal Muscle Innervation
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Figure 10.10a, b
Figure 10.10 Skeletal Muscle Innervation
PLAY
Animation: Neuromuscular junction
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Figure 10.10c
Excitation/contraction coupling
• Action potential along T-tubule causes release of calcium from cisternae of SR • Initiates contraction cycle • Attachment • Pivot • Detachment
• Return
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Figure 10.12 The Contraction Cycle
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Figure 10.12
Figure 10.12 The Contraction Cycle
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Figure 10.12
Figure 10.12 The Contraction Cycle
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Figure 10.12
Figure 10.12 The Contraction Cycle
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Figure 10.12
Relaxation
• Acetylcholinesterase breaks down ACh • Limits the duration of contraction
PLAY
Animation: Sliding filament theory
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SECTION 10-4 Tension Production
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Tension production by muscle fibers
• All or none principle • Amount of tension depends on number of cross bridges formed • Skeletal muscle contracts most forcefully over a narrow ranges of resting lengths
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Figure 10.13 The Effect of Sarcomere Length on Tension
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Figure 10.13
• Twitch • Cycle of contraction, relaxation produced by a single stimulus • Treppe • Repeated stimulation after relaxation phase has been completed
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Summation
• Repeated stimulation before relaxation phase has been completed • Wave summation = one twitch is added to another • Incomplete tetanus = muscle never relaxes completely • Complete tetanus = relaxation phase is eleminated
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Figure 10.14 The Twitch and the Development of Tension
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Figure 10.14
Figure 10.15 Effects of Repeated Stimulations
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Figure 10.15
Tension production by skeletal muscles
• Internal tension generated inside contracting muscle fibers
• External tension generated in extracellular fibers
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Figure 10.16 Internal and External Tension
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Figure 10.16
• 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 The Arrangement of Motor Units in a Skeletal Muscle
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Figure 10.17
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