7 How do muscles contract? The muscular system and the nervous system work together to signal and receive signals from the brain to allow for muscular contraction.The link = neuromuscular junction
8 How do muscles contract? A muscle contraction results from a signal from a nerve impulse.The electrical impulse travels down the neuron and body of the nerve to the neuromuscular junction.(Where the nervous system and the muscle meet)
10 How do muscles contract? Acetylcholine is released and receptors on the muscle fibers detect the chemicals presence and muscle contracts.Within a motor unit (bundle of muscle fibers), all fibers contract at the same time or all fibers are relaxed = all or none principle
13 How our muscle contracts once the message has been recieved Sliding Filament Theory
14 Muscle Structure A muscle is a collection of many microscopic fibers. Each muscle fiber consists of many small fibrils which are composed of even smaller protein filaments. (actin and myosin)Myosin = thicker Actin = thinnerWhen a muscle contracts/shortens the finer/thinner actin filaments slide toward eachother and pass over the myosin filaments.
15 Longitudinal section of myofibril (a) At restSport Books Publisher
16 Sliding Filament Theory When a nerve impulse is received at the muscle (neuromuscular junction) it enters the interior of the fiber via a tuble.The impulse causes the release of calcium ions (Ca++).As a result, the myosin cross-bridges form a type of bond with selected sites on the actin filaments.
17 The Sliding Filament Theory ATP is split and the energy released allows the acting filaments to slide toward each other. Consequently the muscle fiber shortens by about one third of its resting length.
21 Sliding Filament Theory In relaxation phase, the effect of the nerve impulse subsides, calcium ions are removed and the bond between myosin crossbrides and the actin filaments is broken.
22 Beef Muscle Contraction VideoContraction and Relaxation of muscleBeef Muscle Contraction
23 Contractile Machinery: Tendons, origin, insertion In order for muscles to contract, they must be attached to the bones to create movementTendons: strong fibrous tissues at the ends of each muscle that attach muscle to boneOrigin: the point of attachment of the muscle to the bone that does not moveInsertion: the point of attachment of the muscle on the bone that movesSport Books Publisher
25 A. Slow Twitch FibresSuited for repeated contractions during activities requiring a force output of less than 20 to 25 percent of max force outputExamples: lower power activities, endurance eventsSport Books Publisher
26 B) Fast Twitch FibresSignificantly greater force and speed generating capability than slow twitch fibresWell suited for activities involving high powerExamples: sprinting, jumping, throwingSport Books Publisher
27 Relative involvement of muscle fibre types in sport events. Sport Books Publisher
28 Muscle Biopsy Fast Twitch (Type II Fibres) Capillary Blood Slow Twitch VesselsSlow Twitch(Type I Fibres)Sport Books Publisher
29 Muscle Teamwork Agonist (prime mover): Antagonist: Synergist: - Muscle or group of muscles producing a desired effectAntagonist:- Muscle or group of muscles opposing the actionSynergist:- Muscles surrounding the joint being movedFixators:- Muscle or group of muscles that steady joints closer to the body axis so the desired action can occurSport Books Publisher
30 Bending or straightening of the elbow requires the coordinated interplay of the biceps and triceps muscles.The triceps relaxes and the biceps contractsThe triceps contracts and the biceps relaxesSport Books Publisher