Lecture8 copy

Lecture8 copy - Lecture#8(Skeletal Muscle Structure and...

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Unformatted text preview: Lecture #8 (Skeletal Muscle Structure and Function) 18/07/2008 12:21:00 ← I. Muscle types and characteristics ← A. Skeletal muscle • movement, posture, shivering • striated • controlled by somatic motor neurons (voluntary) • very malleable (changeable) usually by training/ disuse (use it or lose it) o hypertrophy: muscle gets larger o atrophy: muscle gets smaller with disuse ← B. Cardiac muscle • heart • striated *both constructed of same kind of components • controlled by autonomic nervous system (involuntary) ← C. smooth muscle • hollow organs, blood vessels • not striated (no sarcomeres) • controlled by autonomic nervous system (involuntary) ← II. Hierarchy and Structure ← A. Hierarchy • Protein filements: actin and myosin • Sarcomere: particular arrangement of actin and myosin ( smallest part that you can shorten) • myofibril: sarcomere end to end • muscle cells (muscle fiber, myofiber) bundles of myofibril • fascicle: group of muscle cells • muscle: particular arrangement of fascicles; at the organ level ← B. Muscle cells • Multi-nucleated • sarcolema o elastic membrane o important for conduction of electrical (neural) signals • sarcoplasm: cell fluid o myofibrils are suspended in sarcoplasm o contains potassium liquid droplets, enzymes and large number of mitochondria • sarcoplasmic reticulum * contains and sequesters calcium (Ca2+) ions ← C. Sarcomere (figure 1+2) • I= isotropic • A= anisotropic • H= helig (light in german) ← III. Contraction ← A. proteins 1. mysocin: thick filements (figure 3) 2. actin: thin filements (figure 4) 3. tropomyosin: long, thin rods 4. troponin: globular protein that sits on tropomyosin (3 subunits)4....
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Lecture8 copy - Lecture#8(Skeletal Muscle Structure and...

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