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 Skeletal which moves the skeleton Smooth which is involuntary and lines the gut and veins Cardiac which makes the heart beat  Tendons  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 PartFunction CartilageReduces friction and absorbs impact Synovial fluidLubricates joint to reduce friction Joint capsuleEncloses the synovial capsule and unites the bones TendonsAttach muscles to bone LigamentsConnect bone to bone Bicep muscleContracts to bend arm Tricep muscleContacts to extend arm HumerusActs as a lever that allows anchorage of the muscles RadiusActs as a lever for the bicep UlnaActs as a lever for the tricep

Elbow movement  Humerus, radius and ulna  Bones of the skeleton  Function as a system of levers  Biceps muscle  Anchored to the shoulder blade and attached to the radius  Contraction flexes the lower arm and stretches the triceps  Triceps muscle  Anchored to the shoulder blade and attached to the ulna  Contraction extends the lower arm and stretches the biceps  Ligaments  Holds bones in the correct position in the joint  Capsule  Contains and protects the joint  Limits its motions  Synovial fluid  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 Triggers the release of calcium ions from the sarcoplasmic reticulum Triggers the removal of the blocking molecule exposing binding sites  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 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