18 - 2 Ca entry triggers the internal release of more Ca from the sarcoplasmic reticulum 3 Ca binds with calmodulin an intracellular protein

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Sheet1 Page 1 Cardiac Muscle - found only in the heart and shares characteristics of both skeletal and smooth muscle 1) cardiac muscle is striated 2) the thin filaments contain tropomyosin and troponin 3) contains an abundance of mitochondria and myoglobin 4) possess T-tubules and sarcoplasmic reticulum 5) Ca++ enters the cytosol from voltage-gated Ca++ channels in the plasma membrane and triggers the further internal releas e 6) displays pacemaker activity initiating its own action potentials 7) connected by gap-junctions 8) innervated by autonomic neuronal fibers 9) action potentials are longer in duration than both smooth and skeletal muscle Excitation-contraction coupling of smooth muscle (Figure 8-29,8-30) 1) self-excitation or neuronal excitation leads to Ca++ entry from the extracellular space through voltage-gated Ca++ channels
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Unformatted text preview: 2) Ca++ entry triggers the internal release of more Ca++ from the sarcoplasmic reticulum 3) Ca++ binds with calmodulin, an intracellular protein similar to troponin 4) the Ca++-calmodulin complex activates myosin kinase which phosphorylates myosin 5) phosphorylated myosin binds to actin to form the activated cross-bridges 6) removal of Ca++ leads to dephosphorylation of myosin and the dissociation of myosin from actin 7) gap-junctions enable excitation of one cell to propagate rapidly to all the coupled cells in a network 8) contraction strength is graded in proportion to the cytosolic Ca++ concentration...
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This note was uploaded on 10/29/2009 for the course NPB NPB 101 taught by Professor Weidner/wingfield during the Fall '08 term at UC Davis.

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