Ryan 1 10 27 15 Anna Ryan Unit 4 A Muscle Movement myosin cross bridges pull actin causing the sarcomere to shorten which causes tension that pulls on the bone attachment sites causing movement a Muscles can only cause movement if the muscle crosses joint and have attachments on either side b Movement role role each muscle takes during movement i Prime Mover Agonist muscle primarily responsible for movement ii Antagonist opposes particular movement iii Synergists muscles that help other muscles by promoting synergy 1 Synergy create something more than just sum of parts 2 Neutralizer neutralizes unwanted movements 2 joint muscles causing different movements at same time no want a EX biceps brachia causes elbow flection and supination but if only want one movement than other muscle cancels the other movement out c Leverage System body functions in movement as a system of levers i Lever type of simple machine that is used to gain advantage in force speed or range 1 Advantage of a lever is you can do less but get more out of it 2 Effort force E force needed to achieve desired movement 3 Resistance force R oppositional force Ex load gravity 4 Fulcrum joint Ryan 2 5 Distance Movement arm MA perpendicular distance from fulcrum to the line representing force a MA longer greater torque shorter smaller torque 6 Force is applied to move the lever and its outcome is determined by the amount of force movement arm distance 7 Torque outcome of the lever or Force x Movement arm distance Torque causes body levers to move the relationship between RT and ET a Resistance Torque resistance force at some distance from fulcrum or Resistance force x Movement arm resistance b Effort Torque Effort Force x Movement arm effort created by muscle pulling on bone to be moved d Muscle Tension i Isometric muscle contraction develops tension without changing length important is postural muscle function antagonist muscle joint stabilization 1 Muscle tension is equal to resistance torque at a standstill no change in length even though the muscles are trying so hard 2 Energy is not used for shortening ii Isotonic Muscle contraction 1 Concentric tension created by shortening caused by prime movers a Muscle tension is greater than resistance torque and is the only way to cause movement Ryan 3 b Least efficient energy use because energy is used for shortening 2 Eccentric tension created by lengthening a Resistance torque is greater than muscle tension the muscle ends up lengthening instead of shortening the muscle acts as a brake trying to slow or control movement b Greatest force is produced because the resistance is doing the work and oxygen use is lower iii Isotonic Tension equal tension muscle creates same amount of tension through ROM but because of lever system body rarely functions this way e Classes of Levers i First Class fulcrum is between effort and resistance 1 Advantages force determined by length of MA s a EMA longer favors force b EMA shorter favors speed and range ii Second Class resistance is between Effort and Fulcrum favors force lets u move large resistance with less effort EMA is always longer than RMA 1 EX wheel barrow iii Third Class Effort is between resistance and fulcrum favors speed and range effort moves slower speed than resistance EMA is always shorter than RMA force is at a disadvantage 1 EX arm Ryan 4 iv Most body levers are third class levers with a few first class levers there are no second class levers f Muscle Twitch response to a single brief threshold stimulus i 1 Latent Period time form stimulation to start of contraction Ca is released and the troponin moves the tropomyosin allowing the cross bridges to attach to the revealed active sites ii 2 Period of Contraction time form onset of contraction to peak tension actin is being pulled by the myosin iii 3 Period of Relaxation no force is generated cross bridges release and the Ca pump working iv There are fast twitch and slow twitch muscles g Graded Concentration graded muscle responses the varying degrees of muscle contraction i Frequency of Stimuli s 2 stimuli in rapid succession the second starts from partly contracted muscle with left over Ca 1 Wave Summation happens when the second twitch is stronger than the first 2 Increasing the stimulation rate results in a shorter relation time and the summation becomes greater eventually leads to no indication 3 Tetanus fused into a smooth sustained contraction that allows of relaxation phase smooth controlled movements Ryan 5 a Most voluntary muscle contractions are short term tetanic contractions ii Strength of stimulus stronger stimulus recruits more motor units there by increasing the number of muscle fibers involved resulting in a stronger contraction 1 Called Multiple Motor Unit Summation Recruitment 2 Treppe stimuli is to far apart to cause wave summation and each resulting contraction is stronger which causes a staircase effect a Results is more Ca and heat forms basis for warm up activities warm up first then stretch h Muscle Tone continual partial contraction muscles always exhibit partial contraction at all times posture shows that they are ready to respond to stimulation B Smooth Muscle a Structural have a single central nucleus short and thin fibers have only a thin endomysium No T tubules poorly developed SR i Caveolae tiny invagination of sarcolemma that keep the Ca ions close ready to trigger contraction ii Very thin actin and myosin that are randomly arranged not causing striation High actin to myosin ratio 13 1 myosin have cross bridges across entire length actin do not have troponin but do have tropomyosin they spiral around fiber with no sarcomeres iii Intermediate filaments attach to dense bodies Ryan 6 iv Dense bands anchor actin along sarcolemma between Caveolae correspond to Z Discs movement results when myosin pulls on actin b Functional Gets Ca from SR and diffuse in extracellular fluid Ca interacts with Calmodulin protein and Kinase enzyme on Myosin head to initiate contraction process c Muscle Contraction i Ca binds to Calmodulin protein to activate it ii Calmodulin activates Kinase enzyme iii Kinase catalysts ATP for energy iv Actin and myosin interact causing slow constrained contractions little energy used fatigue resistance more energy efficient than skeletal muscle needing less ATP and have fewer mitochondria as a result v Stress Relaxation Response skeletal muscle contracts more forcefully when first stretched Smooth muscle contracts when stretched then