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MUSCLES AND MOVEMENT Bozeman muscles Endoskeleton vs Exoskeleton Exoskeleton Found on the outside of the animal Composed of chitin Attachment of muscles is on the inside Allows organisms to lift/jump huge amounts in proportion to their body Endoskeleton Found on the inside of the body Composed of bone Attachment of the muscles in on the outside Definitions Bones Support and partially protect body parts Atriculate with other bones at the joints Provide anchorage for the muscles Consists of the Axial skeleton – skull and vertebral column Appendicular skeleton – limb girdles and limbs Ligaments Hold the bones together Form protective capsules around moveable joints Strong but elastic fibers Definitions cont. Muscle Cause movement by contraction Three types Tendons Skeletal which moves the skeleton Smooth which is involuntary and lines the gut and veins Cardiac which makes the heart beat Attach muscle to the bone Cords of dense connective tissue Nerves Bundles of nerve fibers of individual nerves Connect the central nervous system with the peripheral nervous system Stimulate the muscles to contract Co-ordinates movement Antagonistic Pairs Work in pairs to move the bone Each muscle can accomplish the opposite effect Bicep raises the forearm Tricep lowers the forearm The elbow joint Parts of the Elbow Joint Joint Part Function Cartilage Reduces friction and absorbs impact Synovial fluid Lubricates joint to reduce friction Joint capsule Encloses the synovial capsule and unites the bones Tendons Attach muscles to bone Ligaments Connect bone to bone Bicep muscle Contracts to bend arm Tricep muscle Contacts to extend arm Humerus Acts as a lever that allows anchorage of the muscles Radius Acts as a lever for the bicep Ulna Acts as a lever for the tricep Elbow movement Humerus, radius and ulna Biceps muscle Contains and protects the joint Limits its motions Synovial fluid Holds bones in the correct position in the joint Capsule Anchored to the shoulder blade and attached to the ulna Contraction extends the lower arm and stretches the biceps Ligaments Anchored to the shoulder blade and attached to the radius Contraction flexes the lower arm and stretches the triceps Triceps muscle Bones of the skeleton Function as a system of levers Lubricates the joints Nourishes the cartilage and removes debris Cartilage Firm flexible material Slippery to reduce friction Striated (Skeletal) muscles • • • • Contains multiple nuclei Specialized for contraction Store glycogen Has myoglobin stores (oxygen released during heavy use) • Lots of mitochondria structure of the sarcomere The muscle contraction When the muscle contracts The myofibril is simulated to contract by the arrival of the action potential of a nerve Each charged blubous head (containing an ADP + P) reacts with the binding site on the actin molecule beside it P is shed at this time releasing energy ADP is released creating a rowing movement Triggers the release of calcium ions from the sarcoplasmic reticulum Triggers the removal of the blocking molecule exposing binding sites Pushes the actin filament along Power stroke shortens the myofibril causing a contraction A fresh ATP binds to the bulbous head The charged head detaches from the bulbous end The muscle is once again charged Video of contraction Analyze a micrograph of muscle Troponin and Tropomyosin Tropomyosin Blocks the binding sites on the actin Troponin Attached to the tropomyosin Has binding sites for calcium When calcium binds to the troponin it causes the tropomyosin to uncover the binding sites on the actin which allows contraction Release of calcium is based on nervous system activity Crash Course Muscles