BIOL 3755 Lecture Notes - Lecture 11: Skeletal Muscle, Endoplasmic Reticulum, Myocyte
Document Summary
Muscles: skeletal striated, cardiac striated, smooth not striated. Organization of skeletal muscle: sarcomere, a band myosin, h zone myosin where there is no overlap with actin, m line anchors myosin, z line (disk) anchors actin, defines limit of sarcomere. I band actin where there is no overlap with myosin (on both sides of z line) Moelcualr mechanisms of skeletal muscle contraction: motor unit motor neuron and all skeletal muscle fibers it innervates, can innervates many muscle fibers, each fiber is controlled by branch from only. 1 motor neuron: when action potential occurs in motor neuron, all muscle fibers in its motor unit. Involves 2 channels, 1 in t tubule membrane, other in sr: t tubule channel voltage gated calcium channel known as dihydropyridine (dhp) receptor; acts as voltage sensor, sr channels ryanodine receptor (ryr); calcium release channel. Sequence of events between motor neuron action potential and skeletal muscle fiber.
