NUR 0012 Lecture 26 Ch. 9 Muscular Physiology CompletionOutline of Last Lecture I. Ch. 9 muscular physiologyA. FunctionsB. FeaturesC. Types of muscle cells: skeletal, cardiac, smoothD. CT coverings help direct contractionE. Muscle cells are extremely vascular and innervatedF. Transverse tubulesOutline of Current Lecture I. Ch. 9 muscular physiology cont.A. Sliding filament theoryB. Neuromuscular junctionC. EC-coupling D. Muscle fiber contraction cycleE. Motor units F. Muscle twitchesCurrent LectureI. Ch. 9 muscular physiology cont.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.A. Sliding filament theory: as the heads of myosins reach up and grab actins they pull it, the H zone gets smaller as it contracts, as multiple sarcomeres contract muscle gets shorterB. Neuromuscular junction (motor end plate): where nervous system interacts with muscles1. Acetylcholinesterase: important to clear out acetylcholine 2. Organophosphates: wipe out acetylcholinesterases, poisons that block3. After NMJ, AP’s propogate across sarcolemma, will talk more about in ch. 11, watched a video on propagation of AP (in slide show)a. “All or none”, if not enough stimulus then depolarization dies ofC. EC-coupling (sarcoplasmic reticulum): calcium plays important role1. Excitation-contraction coupling, watched another video on itD. Muscle fiber contraction cycle: will continue as long as ATP is available and calcium is bound to troponin1. Actin binding site exposed2. Power stroke: myosin head pivots and slides actins closer together3. Cross bridge detachment: need more ATP4. Reactivation of myosin head, ATP hydrolyzes to ADP and inorganic phosphate,releasing energy activating myosin head5. Watched video on cross bridge cycle 6. We perceive the contraction as one smooth motion since it happens so quicklyE. Number of motor units varies from muscle to muscle1. Fine muscle control: 1 nerve to 10 or less muscle fibers, extremely fine-tuned control2. Gross muscle control: 1 nerve to hundreds of muscle fibers, big “blocks” of movementF. Muscle twitches occur pretty quickly1. Myogram shows 3 phases of an isometric twitch from some stimulus2. Latent period3. Period of contraction4. Period of relaxation5. What we see is smooth coordinated muscle contractionsa. Temporal summation: allows for smooth graded contractions1) When we signal muscle tissue with multiple AP’s and muscle fibers start contracting so quickly they don’t have time to relax in between, we lose “individual twitchiness” 2) Incomplete tetany: quivering associated with muscle strain3) Complete tetany: can only really be produced artificiallyb. Spatial summation: good for generating force by recruiting a lot of musclefibers at once, if you have many nerve endings coming in at once leads to maximal contraction (multiple AP’s reaching sarcolemma at same time)1) Helps to control the force used by a muscleG. Types of muscle contraction: do not need to know for exam unless he sends us an email out over the
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