10Skeletal muscle microstructure. MyofibrilZ-lineZ-lineSarcomereA closer view of a section of a myofibrilshowing that it is composed ofsarcomeres joined end to end at theZ-line.MyosinActinAn electron micrographcross section of a sarcomerein a region that contains bothactin and myosin.Thin filament(actin)Thick filament(myosin)Sarcomeres contain thin filaments ofactin that attach to the Z-lines andthicker filaments of myosin that spanthe gap between actin molecules.Figure 6.5 Structure of a myofibril.A transmission electron micrograph ( 11,300)of a longitudinal section of a sarcomere. Therounded red objects are mitochondria.10
13Activity 1: Skeletal Muscle Has striated cells with multiple nucleiOccurs in the muscles attached to skeletonFunctions in voluntary movement of bodyExamine figure 1.Identify the long, multinucleated fibers arranged in a parallel fashion. How do you know the muscle fibers are striated?
15Activity 1 Draw a sarcomere. Identify and label the following structures:Z-linesThick and Thin filaments
16Identify the Following Structures: A, B, C, and D.
17Activity 2. Examine the model of the neuromuscular junction. Examine the branching of the motor neuron to several muscle cells.Identify the motor neuron, synaptic cleft, sarcoplasmic reticulum and T- tubules.Draw the neuromuscular junction.
18The release of acetylcholine at the neuromuscular junction causes an Figure 6.61The release of acetylcholine at theneuromuscular junction causes anelectrical impulse to be generatedin the muscle cell plasma membraneMotor neuronAcetylcholine2ElectricalimpulseThe electrical impulse( ) is carriedto the cell’s interiorby the T tubulesCa2T tubuleSarcoplasmicreticulum3The electrical impulsetriggers the releaseof Ca2 from thesarcoplasmicreticulumFigure 6.6 How nerve activation leads to calcium release within a muscle cell.Muscle cellplasmamembraneMyofibrilsZ-line18
19QuestionsHow do a motor neuron and a skeletal muscle fiber join at a neuromuscular junction?What events occur at this neuromuscular junction?
20Activity 3 Examine the figure of a muscle cross section. Identify the following structures: tendon, fascicles, perimysium, epimysium.Draw and label whole muscle.
21Activity 4: observing the gross anatomy of skeletal muscles.
22Pectoralis major Trapezius Serratus anterior Deltoid Biceps brachii Figure 6.1Pectoralis majorDraws arm forwardand toward the bodyTrapeziusLifts shoulder bladeBraces shoulderDraws head backSerratus anteriorHelps raise armContributes to pushesDraws shoulder blade forwardDeltoidRaises armBiceps brachiiBends forearm at elbowTriceps brachiStraightens forearmat elbowRectus abdominusCompresses abdomenBends backboneCompresses chest cavityLatissimus dorsiRotates and drawsarm backward andtoward bodyExternal obliqueLateral rotation of trunkCompresses abdomenGluteus maximusExtends thighRotates thigh laterallyAdductor longusFlexes thighRotates thigh laterallyDraws thigh toward bodyHamstring groupDraws thigh backwardBends kneeFigure 6.1 Major skeletal muscle groups and their functions.SartoriusBends thigh at hipBends lower leg at kneeRotates thigh outwardGastrocnemiusBends lower leg atkneeBends foot away fromQuadriceps groupFlexes thigh at hipsExtends leg at kneeAchilles tendonConnectsgastrocnemiusmuscle to heelTibialis anteriorFlexes foot toward knee22
26IntroductionFunction of the muscular system Types of muscles and functions Basic structure of skeletal muscles Skeletal muscles work in pairs Name and actions of skeletal muscles Leave procedures out
27Results Include your results from each activity. Drawing, label your drawings see the following example.Complete table or box. Label the table and include a description of the table or box.
28Figure 1. Motor neuron anatomy Figure 1. Motor neuron anatomy. Neurons are cells specialized to conduct nerve impulses.
29Conclusion Include motor neuron and motor unit. Include all the components of a neuromuscular junction. How do a motor neuron and skeletal muscle fiber join at a neuromuscular junction? What events occur at the neuromuscular junction? What is the function of ACh?Include the microscopic anatomy of a muscle fiberDescribe the sarcomere(include all the components in a sarcomere)Describe the contraction cycle.What are the roles played by calcium and ATP during muscular contraction?Explain cross-bridge, power stroke and the sliding filament model.What is the function of ATPase?Isometric and Isotonic contractionsComplete the questions page 113 and 114.