Muscle Function and AnatomyFunction of MuscleMuscle ArchitectureHow Are Muscles Built?MyofibrilsSlide 6Muscle FiberSlide 8Slide 9FascicleThe Whole MuscleSlide 12Muscle MembranesTendonsMuscle Fiber Arrangement p. 25Slide 16Types of Muscle Contraction p. 28Types of Muscle ContractionSlide 19Eccentric ContractionSlide 21ROLE OF MUSCLESAgonist and AntagonistTypes of Muscle FibersQuestions?Muscle Function and AnatomyFunction of MuscleMotion of jointsMovement of body fluids - pump blood, peristalsis Regulation of body fluids - bladder Body stability Heat production - 85%Muscle ArchitectureHow Are Muscles Built?In circular sectionsDeepest section contains two proteinsMyosinActinMyosin is surrounded by actinMyofibrilsBundles of actin and myosinMuscle FiberAmong others things, a muscle fiber contains many groups of myofibrilsFascicleA group of muscle fibers bundled together.The Whole MuscleThe Whole MuscleMuscle MembranesTendonsAll 3 membranes converge to form a tendon which connects the muscle to the boneMuscle Fiber Arrangement p. 25Pennate musclesGreater cross sectional area – greater force (strength) productionParallel musclesLonger muscles – greater range of motionParallel muscles1. Flat (rectus abdominus)2. Fusiform (biceps)3. Strap (sartorius)4. Radiate (trapezius)5. SpincterPennate1. Unipennate (biceps femoris)2. Bipennate (rectus femoris)3. Multipennate (deltoid)Muscle Fiber ArrangementStrapTypes of Muscle Contraction p. 28Isometric (Static)Isotonic (Dynamic)ConcentricEccentricTypes of Muscle ContractionConcentric contraction - If muscle force is greater than the resistanceStatic or Isometric contraction - If muscle force is equal to the resistanceEccentric contraction - If muscle force is less than the resistanceLengthensLengthensEccentric ContractionUsed to control agonist and prevent over lengthening of the antagonist.Example: triceps lowers dumbbell while biceps ’controls’ the triceps activity (action).Causes more damage than other typesGreater repair required……producing a stronger muscleAlso, results in more muscle soreness.TABLE 2.1 Type of ContractionIsometricIsotonicConcentric EccentricAgonist muscle No change Shortening LengtheningAntagonist No change Lengthening ShorteningJoint angle No change In direction of force In direction of external resistanceDirection of body part Against immovable objectAgainst gravity or external forceConsistent with gravity or external forceMotion Pressure but no motion Causes motion Causes motionDescription Static Dynamic shortening Dynamic lengtheningMuscle force v. ResistanceF = R F > R F < RSpeed Equal to resistance Faster than the inertia of the resistanceSlower than the speed of gravity or applied inertial forcesAcceleration or DecelerationZero A DSymbol = + -ROLE OF MUSCLESAgonist – prime moverAntagonist – have an action opposite to the agonistStabilizers – fixate or stabilize the jointSynergists – assist or guidingNeutralizers – counteract or neutralize movementsAgonist and AntagonistTypes of Muscle FibersFast twitchSlow
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