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____ Chapter 49 ~ Sensory and Motor Mechanisms

____ Chapter 49 ~ Sensory and Motor Mechanisms. ( Just focusing on motor mechanisms ) Motor Mechanisms. Vertebrate Skeletal Muscle. Contract/relax: antagonistic pairs w/skeleton Muscles: bundle of…. Muscle fibers: single cell w/ many nuclei consisting of….

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____ Chapter 49 ~ Sensory and Motor Mechanisms

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  1. ____ Chapter 49 ~ Sensory and Motor Mechanisms • (Just focusing on motor mechanisms) • Motor Mechanisms

  2. Vertebrate Skeletal Muscle • Contract/relax: antagonistic pairs w/skeleton • Muscles: bundle of…. • Muscle fibers: single cell w/ many nuclei consisting of…. • Myofibrils: longitudinal bundles composed of…. • Myofilaments: • Thin~ 2 strands of actin protein and one strand of a regulatory protein • Thick~ staggerd arrays of myosin protein http://entochem.tamu.edu/MuscleStrucContractswf/index.html

  3. Vertebrate Skeletal Muscle • Sarcomere: repeating unit of muscle tissue, composed of…. • Z lines~sarcomere border • I band~only actin protein • A band~actin & myosin protein overlap • H zone~central sarcomere; only myosin http://www.sumanasinc.com/webcontent/animations/content/muscle.html

  4. Sliding-filament model • Theory of muscle contraction • Sarcomere length reduced • Z line length becomes shorter • Actin and myosin slide past each other (overlap increases) http://www.blackwellpublishing.com/matthews/myosin.html

  5. Actin-myosin interaction • 1- Myosin head hydrolyzes ATP to ADP and inorganic phosphate (Pi); termed the “high energy configuration” • 2- Myosin head binds to actin; termed a “cross bridge” • 3- Releasing ADP and (Pi), myosin relaxes sliding actin; “low energy configuration” • 4- Binding of new ATP releases myosin head • Creatine phosphate~ supplier of phosphate to ADP

  6. Muscle contraction regulation, I • Relaxation: tropomyosin blocks myosin binding sites on actin • Contraction: calcium binds to toponin complex; tropomyosin changes shape, exposing myosin binding sites http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__action_potentials_and_muscle_contraction.html

  7. Muscle contraction regulation, II • Calcium (Ca+)~ concentration regulated by the…. • Sarcoplasmic reticulum~ a specialized endoplasmic reticulum • Stimulated by action potential in a motor neuron • T (transverse) tubules~ travel channels in plasma membrane for action potential • Ca+ then binds to troponin

  8. Materials Muscle model/chicken wing • The following is needed for each student: 4 red/black licorice strands (the thick twisted type) • 10 red licorice strands (the thin type) • a paper towel; toothpicks • one raw chicken wing • one dissection tray; dissection tools, gloves.

  9. Muscle cell simulation: contraction/relaxation • Procedure: • Two thin pieces of licorice intertwined to represent thin actin filaments • Thick licorice to represent thick myosin fibers • Toothpicks represent the Z lines where thin filaments attach

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