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Unformatted text preview: Lecture 6 Smooth Muscle non voluntary I. Myofiber Anatomy 1. Size diameter 2 5 length 50 100 (1 nucleus) 2. Myofilaments Not striated Random pattern of actin and myosin Less crowding Longer actin/myosin filaments shorten 50-70% of original length II. APs a lot of smooth muscle cells dont fire APs 1. Depolarization based on ions floating across membrane L (long acting) type Ca++ channels open up Ca++ influx Ca++ channels stay open longer than Na+ channel 2. Repolarization based on opening up of K+ channels 3. Slow wave depolarization at rest (drifts towards threshold on its own) pacemaker Beating frequency muscle can develop on its own Zaps on its own 4. Spread of depolarization no T-tubules Gap junctions electrical connections that connect cells Act as syncition (fire together) III. Contraction Long duration sec-min multiple APs, almost like summation twitches Slow myosin-actin interaction...
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- Winter '08