Muscles and Muscle TissueOverview of Muscle TissueSlide 3Skeletal Muscle TissueCardiac Muscle TissueSmooth Muscle TissueDifferences in ContractionsMuscle FunctionsProducing MovementMaintaining PostureStabilizing JointsGenerating HeatFunctional CharacteristicsSkeletal MuscleAnatomy of a Skeletal MuscleConnective Tissue WrappingsSlide 17Slide 18Nerve and Blood SupplyAttachmentsSlide 21Contraction of Skeletal MuscleThe Motor UnitSlide 24Slide 25Slide 26Skeletal Muscle FiberSlide 28Myofibrils and SarcomeresSlide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Types of Skeletal Muscle FiberSlide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Next SectionSmooth MusclesSlide 47Slide 48End of ChapterMuscles and Muscle TissueChapter 9Overview of Muscle TissueThere are three types of muscle tissue–Skeletal muscle–Cardiac muscle–Smooth muscleThese muscle tissues differ in the structure of their cells, their body location, their function, and the means by which they are activated to contractOverview of Muscle TissueAll skeletal and smooth muscle cells are elongated and are referred to as muscle fibersMuscle contraction depends on two types of myofilaments, actin and myosinAll prefixes of myo or mys and sarco reference muscleSkeletal Muscle TissueSkeletal muscle tissue appears as distinct skeletal muscle that attach to the skeletal systemSkeletal muscle has obvious striationsIt is a voluntary muscle under conscious controlCardiac Muscle TissueCardiac muscle occur only in the heartThe muscle is striated but involuntaryCardiac fibers are short, fat, branched and interconnectedCardiac muscle cells are interlocked by intercalated discs and function as a single unitSmooth Muscle TissueIt is found in the walls of hollow organs such as the stomach, urinary bladder, and intestinesIt has no striationsIt is not subject to voluntary controlDifferences in ContractionsSkeletal muscle can contract rapidly but tire easily and must be restedSkeletal muscle contractions vary in force depending on useCardiac muscle contracts at a steady rate but can accelerate to cope with demandSmooth muscle contracts in steady, sustained contractions and continues on tirelesslyMuscle FunctionsMuscle performs four important functions in the body:–Producing movement–Maintaining posture–Stabilizing joints–Generating heatProducing MovementMovement results from skeletal muscle contractionSkeletal muscle are responsible for all locomotion and manipulationAllows you to interact or react with your external environmentIt controls eye movement, facial expression (skeletal); circulation (cardiac), and moves gas, liquids, and solids through organs (smooth)Maintaining PostureSkeletal muscles are utilized constantly to maintain sitting, standing, and moving posturesPostural muscle develop to compensate for the never ending pull of gravity–Our developmental milestones as an infant are our initial victories over gravityCurves of the spinal column are shaped by the interplay of skeletal muscle and gravityStabilizing JointsSkeletal muscle provide the dynamic stability of jointsMany joints are poorly reinforced by ligaments and connective tissueMany joints have noncomplementary surface which do not contribute to stabilityGenerating HeatMuscles generate heat as they contractThe heat generated is vitally important to maintain normal body temperatureSkeletal muscle generates most of the heat because it represents 40% of body massExcess heat must released to maintain body temperatureFunctional CharacteristicsExcitability or irritability–It has the ability to respond to a stimulusContractility–It has the ability to shorten forciblyExtensibility–Muscle fibers can be stretchedElasticity–Resume its normal length after being shortenedSkeletal MuscleAnatomy of a Skeletal MuscleEach skeletal muscle is a discrete organ with thousands of fibersMuscle fibers predominate the tissue but it also contains, blood vessels, nerve fibers, and connective tissueConnective Tissue WrappingsEach muscle fiber is wrapped by fine sheath of areolar connnective called endomysiumSeveral fibers are gathered side by side into bundles called fasciclesEach fascicle is bound by collagen a fiber layer called the perimysiumConnective Tissue WrappingsFascicles are bound by a dense fibrous connective tissue layer called the epimysiumThe epimysium surrounds the entire muscleExternal to the epimysium is the deep fascia that binds muscles into functional groupsConnective Tissue WrappingsAll the connective tissue layers are continuous with one another as well as with the tendons that join muscles to boneWhen muscle fibers contract they pull these connective tissue sheaths which in turn transmit the force to the bone to be movedConnective tissues supports each cellNerve and Blood SupplyNormal activity of skeletal muscle is totally dependent on its nerve and blood supplyEach skeletal muscle fiber is controlled by a nerve ending (neuromuscular junction)Contracting muscle fibers use huge amounts of energy which requires a continuous supply of oxygen and nutrientsIn general, each muscle is served by an artery and one or more veinsAttachmentsMost muscles span joints and have at least two attachments an origin and an insertionOrigin–Attachment of a muscle that remains relatively fixed during muscular contraction–Generally a more proximal or axial locationInsertion–Attachment of a muscle that moves during muscular contraction–Generally a more distal or appendicular attachmentAttachmentsDirect attachments have the epimysium attaching directly to the periosteum of the bone or perichondrium of a cartilageIndirect attachments have the epimysium attaching to a tendon or an aponeurosisTemporalis has both muscle attachmentsContraction of Skeletal MuscleThe principles of contraction of a muscle cell can be generalized to the entire muscleThe force exerted is called tension, the resistance to the force is called the loadA contracting muscle does not always shorten (isometric or isotonic)Skeletal muscle can contract with varying force for different periods of time which enhances its efficiencyThe Motor UnitEach muscle is served by at least one motor nerve which contains hundreds of motor neuron axonsAs a nerve enters a muscle it branches into a number of axonal terminals, each