BSCI 201 Lecture Notes - Lecture 26: Parasympathetic Nervous System, Sarcomere, Sympathetic Nervous System
8 Nov 2016
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Lacks striations because the thin/thick filaments are not arranged in the alternating pattern: thin/thick filaments are arranged diagonally down the smooth muscle cell. T-tubules are absent instead shallow concavities of the sarcolemma of a smooth muscle cell called caveolae (caveoli) contain calcium rich extracellular fluid cisternae. Smooth muscle cells has poorly developed sr with no terminal cisternae: no t tubules, so no terminal cisternae. Z discs are absent, so instead thin filaments are anchored by dense bodies: since z discs are absent, smooth muscle cells do not contain sarcomeres. Troponin is absent: tnc, tnt, tni- all of this is absent, so ionic calcium binds to another regulatory protein called carmodulin. In a relaxed smooth muscle tropomyosin does not block myosin binding site on actin. E-c coupling in smooth muscle: a smooth muscle can be activated to contract by. Pacemaker activity intrinsic autorhythmic cells that spontaneous depolarize to generate potentials (skeletal muscles lacks pacemaker activity)
