Date post: | 24-Dec-2015 |
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Skeletal Muscle
• Long cylindrical cells• Many nuclei per cell• Striated• Voluntary• Rapid contractions
Cardiac Muscle
• Branching cells
• One or two nuclei per cell
• Striated
• Involuntary
• Medium speed contractions
Smooth Muscle
• Fusiform cells
• One nucleus per cell
• Nonstriated
• Involuntary
• Slow, wave-like contractions
Muscle Contraction Summary
• Nerve impulse reaches myoneural junction
• Acetylcholine is released from motor neuron
• Ach binds with receptors in the muscle membrane to allow sodium to enter
• Sodium influx will generate an action potential in the sarcolemma
Muscle Contraction Continued
• Action potential travels down T tubule
• Sarcoplamic reticulum releases calcium
• Calcium binds with troponin to move the troponin, tropomyosin complex
• Binding sites in the actin filament are exposed
Muscle Contraction Continued
• Myosin head attach to binding sites and create a power stroke
• ATP detaches myosin heads and energizes them for another contaction
• When action potentials cease the muscle stop contracting
Muscle Fatique
• Lack of oxygen causes ATP deficit
• Lactic acid builds up from anaerobic respiration
Muscle Atrophy
• Weakening and shrinking of a muscle
• May be caused– Immobilization– Loss of neural stimulation
Muscle Hypertrophy
• Enlargement of a muscle
• More capillaries• More mitochondria• Caused by
– Strenuous exercise
– Steroid hormones