Movement

Movement Movement State the roles of the following structures in human movement Provide anchorage for muscle attachment and act as levers Bones: ……………………………………………………………………………………………………………………………………………. Connect bone to bone Ligaments: ……………………………………………………………………………………………………………………………………… Connect bone to muscle Tendons: ………………………………………………………………………………………………………………………………………… Provide the force required for the movement of bones Muscles: …………………………………………………………………………………………………………………………………………. Label the following diagram of a human elbow joint Humerus 1. ……………………………………………………………… Bicep 2. ……………………………………………………………… Tricep 3. ……………………………………………………………… Joint Capsule 4. ……………………………………………………………… Cartilage 5. ……………………………………………………………… Radius 6. ……………………………………………………………… Ulna 7. ……………………………………………………………… Explain why movement requires antagonistic muscle pairs Muscles can only cause movement by contracting (i.e. muscles cause movement in one direction) ………………………………………………………………………………………………………………………………………………….......... In order to enable opposing movements, muscles must work in antagonistic pairs (one contracts, one relaxes) ………………………………………………………………………………………………………………………………………………….......... Muscles Describe the structure of a muscle fibre Skeletal muscles consist of bundles of muscle fibres (formed of fused cells) that have key features: ………………………………………………………………………………………………………………………………………………….......... Multinucleated - Muscle fibres are formed from multiple individual muscle cells fusing together ………………………………………………………………………………………………………………………………………………….......... Large number of mitochondria - Contraction requires ATP expenditure ………………………………………………………………………………………………………………………………………………….......... Tubular myofibrils - Tubular myofibrils run the length of the fibre and are responsible for contraction ………………………………………………………………………………………………………………………………………………….......... Sarcolemma - The sarcolemma is the continuous membrane surrounding a muscle fibre ………………………………………………………………………………………………………………………………………………….......... Sarcoplasmic reticulum - Internal membrane network that is specialised for muscle contraction (high calcium) ………………………………………………………………………………………………………………………………………………….......... Draw and label a diagram to show the structure of a sarcomere Outline the process of muscle contraction Action potential in a motor neuron triggers the release of Ca2+ ions from the sarcoplasmic reticulum ………………………………………………………………………………………………………………………………………………….......... Calcium bind to troponin (on actin) and cause tropomyosin to move, exposing binding sites for myosin heads ………………………………………………………………………………………………………………………………………………….......... The actin filaments and myosin heads form a cross-bridge that is broken by ATP ………………………………………………………………………………………………………………………………………………….......... ATP hydrolysis causes the myosin heads to swivel and change orientation ………………………………………………………………………………………………………………………………………………….......... Swiveled myosin heads bind to actin filament before returning to their original conformation (releasing ADP) ………………………………………………………………………………………………………………………………………………….......... The repositioning of the myosin heads move the actin filaments towards the centre of the sarcomere ………………………………………………………………………………………………………………………………………………….......... The sliding of actin along myosin therefore shortens the sarcomere, causing muscle contraction ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Identify the state of contraction in the following muscle fibres Relaxed (wide I bands and visible H zone) …………………………………………………………………….. Contracted (narrow I bands and no H zone) ……………………………………………………………………