Presentation on theme: "Neuromusculoskeletal System"— Presentation transcript:
1Neuromusculoskeletal System VCE PE Units 1 & 2Neuromusculoskeletal SystemMuscle formation, recruitment and contraction
2KEY KNOWLEDGE KEY SKILLS Key Knowledge and skills The way the neuromuscular and musculoskeletal systems work together to bring about movements including major bones, muscles, joints and joint actionThe various characteristics of the different muscle types – fibre and arrangementIsotonic, isokinetic and isometric muscle contractionsThe agonist and antagonist relationship as related to reciprocal inhibition and the associated use of stabilisersThe nervous control of muscles including recruitment of motor units, fibres and types of contractionCorrect use of anatomical terms related to major bones, muscles, common joints and their actions that bring about movements.Participate in and analyse a broad range of movements used in sporting activities and be able to identify key bones, muscles and joint movements associated with those movements.Explain and discuss how reciprocal inhibition worksIdentify the different types of muscle fibres and contractions responsible for a wide range of physical activities performed at varied intensities
3Learning Intentions Strengthen your understanding of the musculoskeletal systemTo learn the characteristics of a motor unitincluding how it is controlled
4Muscle fibre arrangement Fusiform- Run longitudinally with the tendon.E.g. Biceps in the armProduce low force but can shorten over a long rangePenniform- run at angles to tendon.Can produce greater force with a higher number of fibersDivided into 3 groups:Unipennate (fibers branch out to one side of the tendon)E.g. GastrocnemiusBipennate (Fibers branch out to both sides of the central tendon)E.g. QuadricepsMultipennate (fibers branch out repeatedly from a number of tendons)E.g. Deltoid
5Muscle fibre arrangement Using what you have learnt, label the following muscle fibre types
9Neuromuscular Junction A single muscle contraction is initiated by an electrical signal inthe CNS (Central Nervous System) that is transmitted along athreadlike axon of a motor unit to a group of skeletal muscle fibres.when the signal reaches the end of a motor unit, it must cross a ‘gap’before it can stimulate the skeletal muscle fibre to contract.This “gap” is called the neuromuscular junction (NMJ).A chemical know as the neurotransmitter assists in carrying theElectrical signal across to the adjacent muscle fibre.A momentary change in cell voltage then results in actionpotentials spreading across the skeletal muscle fibre which resultsin contraction and force production.A stronger stimulus will produce a greater number of actionpotentials per second and a stronger contraction.
11Microscopic Structure of a Skeletal Muscle worksheet
12Nervous control of muscular contractions Motor neurons convey nerve impulses form the brain to musclesA motor neuron and the fibres it controls/stimulates are known as the motor unitSensory neurons convey nerve impulses from muscles, organs and cells to the brain
13The all or nothing principles states: It is not until an electrical threshold is surpassed that all of the fibres linked to a motor unit will fire together and maximally.Gross movements requiring major muscle involvement require more motor units than precise/ fine movementsFibres will be recruited according to the activity demand and this is known as preferential recruitment
14Sliding Filament Theory *How muscles contract*Myofilaments sliding across each otherSteps:Electrical impulse sent from brain to the synapse of individual myofibrils[neuromuscular junction]Acetylcholine activates the release of calcium ionsThis stimulates oar-like projections call ‘Cross-bridges’ to reach out and attachto the actin filamentsCross bridges shorten and pull actin filaments towards the centerThe muscle contracts(SFT song)
15The effect of muscle contraction on structures of the sarcomere Sarcomere regionMuscle shorteningMuscle lengtheningA bandUnchangedI bandShortensLengthensH zoneShortens and disappearsReappears and lengthensZ line
17Thinking Things Through Pg. 22Questions: 1,2,3,4,5
18Types of ContractionThere are basically three types of muscular contraction, classified by the movement they cause. These are listed below in order of occurrence in everyday activity, from most common to least common:• isotonic (concentric and eccentric)• isometric• isokineticlsotonic contractionOccurs whenever the muscle length changes through a range of motion or action. When a constant load (weight) is being moved, differences exist in the amount of force applied at various joint angles.Isometric contractionOccur when tension is developed but no change results in the length of the muscle. Isometric contractions hence involve little, if any, change in muscle length while tension is developed.lsokinetic contractionTension developed is maximal throughout the entire range of motion and is common on hydraulic fitness equipment. The amount of force applied by the machine always equals the amount of force applied by the muscle.
19Fast & Slow Twitch Fibres Muscles are made up of two different types of fibres:• Red, type I, slow-twitch fibres (ST), best suited to aerobic, endurance work such as triathlons.• White, type II, fast-twitch fibres (FT), best suited to short-duration, high intensity anaerobic work, for example the bursts of power and speed required to sprint.
21Fibre Recruitment Theory Recruitment: The progressive activation of a muscle by consecutiveactivation of motor unitsi.e. When the muscle is first activated, the earliest motor units tofire will be small in size with progressively larger units recruited asthe strength of muscle contraction is increased.To measure the neural activity of muscle you use anElectromyography (EMG). An EMG records both the quality andquantity of electrical activity within a muscle.