BIO 203 Lecture Notes - Lecture 13: Dihydropyridine, Ryanodine, Cytosol
16 Nov 2016
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Cells bundled into fascicles surrounded by connective tissue. Light and dark bands seen under light microscopy. One sarcomere between by two z disks. I band is made of thin filaments only (actin) A band is made of darker regions where both light and heavy filaments overlap. H zone is a clear band in the middle of the a band, heavy filaments only. M line represents the proteins to which heavy filaments attach. Acetylcholine (ach) is released from the somatic motor neuron. Ach binds to receptors on the sarcolemma. Na+ and k+ ions flow in the cell. Depolarization of the muscle fiber membrane creates an end-plate potential (epp) The epp is always suprathreshold for generating an action potential in the skeletal muscle fiber. Thus, the nmj has a high safety factor. L-type calcium channel dihydropyridine (dhp) receptor and ryanodine receptors (ryr) A muscle twitch is a single contraction-relaxation cycle.
