muscle tissue cont. physiology chapter 10
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Muscle Tissue Cont. Physiology Chapter 10. Contraction of Skeletal Muscle = The Sliding Filament Mechanism. thin and thick filaments slide past each other to shorten each sarcomere and thus each myofibril the cumulative effect is to shorten the muscle. - PowerPoint PPT PresentationTRANSCRIPT
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Muscle Tissue Cont.
Physiology
Chapter 10
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Contraction of Skeletal Muscle = The Sliding Filament Mechanism
• thin and thick filaments slide past each other to shorten each sarcomere and thus each myofibril
• the cumulative effect is to shorten the muscle http://www.lab.anhb.uwa.edu.au/mb140/
CorePages/Muscle/Muscle.htm#SKELETAL
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Skeletal Muscle InnervationThe Neuromuscular
Junction: • where neurons communicate
with the muscle fibers • point of communication is a
small gap = synapse• the chemical that travels
across the synapse = neurotransmitter (acetylcholine - ACh)
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Steps of Skeletal Muscle Contraction
1. Neurotransmitter ACh is released from the neuron; binds to its receptor on the sarcolemma, and causes the sodium channels to open
ha5lf0909ab_a.jpg
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Steps of Skeletal Muscle Contraction
2. As Na+ ions flow in, an action potential begins
action potential = the spread of depolarization
3. ACh removed by enzyme acetylcholinesterase
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Steps of Skeletal Muscle Contraction 4. Action potential causes
release of Ca++ ions 5. Ca++ binds to troponin,
causing tropomyosin to move out of its blocking position
6. Contraction: myosin forms cross bridges to actin, muscle shortens, ATP is used
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Steps of Skeletal Muscle Contraction
7. Ca++ ions are reabsorbed
8. Myosin binds to new ATP
9. Troponin-tropomyosin complex returns to normal position
10. Contraction ends; muscle returns to its resting length
STUDY FIG. 10.11 p. 317
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Skeletal Muscle Contraction = Sliding Filament Theory
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The Contraction Cycle Animation
http://www.sci.sdsu.edu/movies/actin_myosin_gif.html
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Rigor Mortis
• When death occurs, Ca++ ions leak and cause some contraction of the muscles = stiffness
• Without ATP, cross-bridges cannot detach
• Lasts ~24 hours, then lysosomal enzymes break down myofilaments
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To help you memorize muscles, check out:
• http://msjensen.education.umn.edu/webanatomy/
University of Minnesota, WebAnatomy
• With your laptop, check out: www.gwc.maricopa.edu/class/bio201/muscle/mustut.htm