Transcript Chapter 10, part 2

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
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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