Muscle Structure And Function PDF

CHAPTER 5 Muscle Structure and Function Kinesiology Books Publisher 1 TABLE OF CONTENTS Types of Human Muscle Skeletal Muscle Properties Muscle Teamwork Structure Muscle Fib...

CHAPTER 5 Muscle Structure and Function Kinesiology Books Publisher 1 TABLE OF CONTENTS Types of Human Muscle Skeletal Muscle Properties Muscle Teamwork Structure Muscle Fibre Types Nerve–Muscle Interaction and Adaptation to Exercise Motor Unit Intramuscle Coordination Intermuscle Coordination Sport-Specific Training Muscle’s Adaptation to Strength Training Kinesiology Books Publisher 2 TYPES OF HUMAN MUSCLE · All three allow for movement ↳ tissue Skeletal Cardiac Smooth (v) isu Girl (S) 3 Kinesiology Books Publisher 3 SKELETAL MUSCLE Properties Teamwork Structure Fibre Types Kinesiology Books Publisher 4 PROPERTIES M bound together Formed by muscle fibres ↳ cell of the muscle Tendons ↳ fibrous connective tissue that attaches muscle to bone During contraction? ↳ once the muscle fiber is stimulated by the motor neuron , actin and myosin , protein filaments within the Skeletal muscle fiber slide past each other to produce a contraction Kinesiology Books Publisher 5 MUSCLE TEAMWORK Skeletal muscles work together in synchrony to produce a desired movement ↳ work as teams Kinesiology Books Publisher 6 AGONIST - ANTAGONIST ↳ Prime mover opposit movement Elbow FLEXION g hamstring e. curls 7 Kinesiology Books Publisher 7 SYNERGIST AND FIXATORS EXAMPLE: Prime mover / agonist contracts to flex shoulder: pectoralis major Xe g Synergist contracts to complement flexion: deltoid anterior. ↳ help with movement Fixator contracts to steady scapula closer to body: serratus anterior L Stabilizers 8 Kinesiology Books Publisher 8 STRUCTURE Muscle belly and cells Contractile units Kinesiology Books Publisher 9  ofpulpoe) Muscle Fibre Bundle ↳ Fascicle diameter Muscle belly hair) of a human Muscle fibre (diameter ↳ runs length of the mussle Myofibrils contractile ↳ holds protein Tendon Sarcolemma 10 term for / muscle Kinesiology Books Publisher 10 THE CONTRACTILE MACHINERY Myofibril Sarcomere Sarcomere ↳ contractile in Series ↳ organized unit Myofilaments Thin filaments = actin proteins 2 what allows Thick filaments = myosin proteins S contraction 11 Kinesiology Books Publisher 11 Thin filament Actin molecules Actin strand Troponin Tropomyosin Sarcomere MYOFIBRIL H zone Myosin head actin ↳ will grab and pull along it Myosin tail Thick filament Myosin molecule  Skeletal muscle = striated muscle Alternating light and dark bands under microscope Due to organization of sarcomeres and myofilaments Sarcomere Z line: Proteins anchoring H zone: M line: Proteins anchoring thin filaments space between thick filaments thin filaments * Watch video I band: A band: I band: Actin filaments Myosin filaments Actin filaments dark Light in color where they are is Thin filament Z line Sarcomere Z line M line H zone Thick filament SLIDING FILAMENT THEORY Muscle contraction occurs due to actin sliding over myosin to active myosin attaches - cross bridge formation - head of the relaxed contracted 15 so the entire muscle Fiber Shortens · pulling Kinesiology Books Publisher 15  A band H zone I band A band H zone I band I band - can generate more strength in some angles and less in others Optimal joint Large joint Small joint angle angle angle · Around 900 weak · strongest · 17 Kinesiology Books Publisher 17  18 Kinesiology Books Publisher 18  MUSCLE FIBRE TYPES muscle you will have both types within - a single Fast twitch Slow twitch O O 0000o muscle fibres muscle fibres Type II Type I deal of force · generate a great · ContractSlower as much force cannot produce hyporture more · · larger resistant · fatigue · fatigue very quickly · clot of blood goes to these anaerobic relay on the aerobic systems · explosive use for posture and long duration activities faster red · contract appear * train your hybrid white appear more · Don't really grow fibers to change from the two · can grow · More myoglobin · less myoglobin Kinesiology Books Publisher 19 Although muscle fibres can't change from one type to another, you can improve what fibres you do have with training. 20 Kinesiology Books Publisher 20 MUSCLE BIOPSY Biopsy = bio (life) + opsis (sight) A tiny piece of muscle is removed and analyzed under a microscope 21 Kinesiology Books Publisher 21 NERVE–MUSCLE INTERACTION AND ADAPTATION Motor Unit Intramuscle Coordination Intermuscle Coordination Sport-Specific Training Muscle’s Adaptation Kinesiology Books Publisher 22 NERVOUS SYSTEM · will activate muscle fibers Central nervous system Sensory nerves: Peripheral nervous system Motor nerves: 23 Kinesiology Books Publisher 23 MOTOR UNIT Motor unit Alpha motor neuron and muscle fibres Delicate and precise movement Many (1,500-3,000) motor units per muscle Few (8-50) muscle fibres per unit Unrefined and powerful movements Few (600-2,000) motor units per muscle Many (1,500) muscle fibres per unit Kinesiology Books Publisher 24  ↳. will activate certain fibers · only need some fibers you will need ones last · activate smaller units first/larger ↳ only will be activated one motor neuron by Motor end plate End of a motor neuron Transmits neural impulses to a muscle fibre units motor has many muscle · every Kinesiology Books Publisher 25 ALL-OR-NONE PRINCIPLE All muscle fibres that make up a single motor unit will contract maximally if the magnitude is reached none) ↳. they are either all activated or all not (all or unit · within that motor Kinesiology Books Publisher 26 ACTIVATION THRESHOLD to · has to hit that threshold fire Every motor unit has a specific threshold · smaller units have a lower activation threshold More Motor units · More force = that must be reached for activation Kinesiology Books Publisher 27 ACTIVATION THRESHOLD Endplate: electrical current triggers a chemical reaction Acetylcholine is released (in the space between) diffuses across the neuromuscular junction excites the sarcolemma Calcium ions are released ↳ cover of the muscle fibers Troponin and tropomyosin change shape and Position expose the active sites on actin Cross bridge binding and muscle contraction occur Kinesiology Books Publisher 28 INTRAMUSCLE ↳ COORDINATION within Capacity to activate different motor units simultaneously Impossible to simultaneously activate all motor units of a muscle Trained athletes: 85% Untrained individuals: 60% time at the same · Muscle fibers fire Motor units fire · together · More motor units will fire Kinesiology Books Publisher 29 INTERMUSCLE COORDINATION Capacity to activate different muscles to produce movement Agonists and antagonists · better at get↳ Allows using the right muscle you to generate more force Kinesiology Books Publisher 30 MUSCLE’S ADAPTATION TO STRENGTH TRAINING - rapidly more fire ⑧ bigger ) improve become Trainable factors: fibre diameter, intra- and inter-muscle coordination, nerve impulse frequency, muscle and tendon elasticity, energy stores, capillary density ↳ gas exchange Non-trainable factors: muscle fibre number and type structure ↳ * if can not add (fibers) type ↳ cannot the change you damage muscle you can't get them back ? Kinesiology Books Publisher 31 PUTTING IT ALL TOGETHER Muscles attached to bones enable movements Myofibrils constitute muscles and enable skeletal muscle contraction Motor units require a threshold or nerve impulse to cause contraction Movement requires precise intra- and inter- muscle coordination Kinesiology Books Publisher 32