2010 MUSCLE Complete +lab - MUSCLE Roger J. Bick Reading:...

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MUSCLE Roger J. Bick Reading: Gartner and Hiatt Chapter 6 - p103-124, Klein and McKenzie pp117-130 Learning Objectives: From lecture and lab you should be able to: 1. Describe ultrastructural and histological characteristics of skeletal, cardiac and smooth muscle. 2. Understand cellular and macromolecular mechanisms governing regulated muscle contraction. 3. Understand basic adaptive and regenerative capacities of each muscle type. 4. Name specialized structures – spindle, etc Key Words: Skeletal, smooth, cardiac, striated, intercalated disc, t-tubule, sarcoplasmic reticulum, sarcolemma, epi-, peri-, and endomysium. Fast twitch v slow twitch. Glycolytic, oxidative. Z, I, A, H and M bands. Actin, myosin, actinin. Intermediate filaments, sarcomere, calmodulin There are three human muscle types: Skeletal: striated, usually voluntary contractions Cardiac: striated, involuntary Smooth: nonstriated, involuntary Point 1- Skeletal and cardiac muscles are BOTH striated, BUT cardiac fibers branch Point 2 - position of nuclei - Smooth and cardiac centrally located, skeletal on the periphery as shown bel ow
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Point 3 for comparison – Skeletal and cardiac have long fibers; smooth muscle has individual, distinct cells. Both cardiac and skeletal are striped (but not smooth); both cardiac and smooth muscle have centrally located nuclei (not skeletal). Gartner and Hiatt page109 Macroscopic Features of muscle. 1. Skeletal Muscle (striated, voluntary) Fiber: Each fiber is an elongate, multi-nucleate cell; from embryonic fusion of 100's of myoblasts. Individual fibers (cells) are 10-120 μ M in diameter and up to 30 cm long (long muscles of upper and lower extremities). Each fiber is surrounded by thin layer of connective tissue, the endomysium (Gr. endo, within; mys, muscle), synthesized primarily by fibroblasts. Muscle fascicle : (L. fasces, bundle) A group of fibers surrounded by a thicker connective tissue sheath, the perimysium (Gr. peri, around). Muscle : Bundle of fascicles surrounded by a thick, connective tissue epimysium (Gr. epi, upon). Muscle grouped as broad sheets (rectus abdominis), or in bundles (biceps), or in circular arrays (obiscularis oris, anal and urinary sphincters).
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And here is the whole thing put together, Contraction is parallel to orientation of fibers. Strength, endurance and fine control dependent on number, size and type of innervation (see below). Pink-red color of muscle due to blood supply and myoglobin content. Contractile force transmitted to bone or other muscle via myotendonal junctions, then connective tissue tendons. Unlike other skeletal muscles, contraction of the diaphragm is involuntary , e.g. during sleep. Skeletal muscle types : Most mammalian skeletal muscle is a mixture of three fiber types: fast twitch, glycolytic (FG; white like chicken breast meat), slow twitch, oxidative (SO; red, like a drumstick) and fast twitch, oxidative-glycolytic (FOG; intermediate type, possessing characteristics of both FG and SO (Sometimes referred to as mixed muscles). Innervation (fast or slow acting) determines fiber type.
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2010 MUSCLE Complete +lab - MUSCLE Roger J. Bick Reading:...

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