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MUSCULAR SYSTEM pp. 917-920 FUNCTION • Support, movement, and protection TYPES • skeletal – muscles that move bones (voluntary) • smooth – involuntary muscles that protect organs • cardiac – involuntary muscles found only in heart MUSCLE STRUCTURE (external) • Tendons connect muscle to bone • When the muscle moves, the bones move, and the joint bends MUSCULAR MOVEMENT • Muscles arranged in opposing pairs and while one relaxes the other contracts flexor: contraction bends the joint extensor: contraction straightens the joint MUSCLE STRUCTURE (internal) myofibril muscle cell (fiber)fascicle muscle • Two types of proteins (actin and myosin) involved • actin + myosin myofibril • myofibril attaches to Z line • sarcomere: functional unit from Z line to Z line MUSCLE CONTRACTION • contraction: shortening of sarcomere between Z –lines • myosin “heads” walk along the actin • this requires ATP to walk and to release the myosin after walking ENERGY and FATIGUE • • Aerobic respiration: breaking down organic compounds to release energy to be used by the body Fatigue is the inability to contract (and release) the muscle due to the lack of ATP SKELETAL SYSTEM pp 911-916 FUNCTION • • • Bones supports and protects organs Gives shape and structure to the body Produce red and white blood cells SKELETON • Axial –the skull, face, vertebral column, and rib cage. • Appendicular –the arms and legs, pelvis, scapula, collar bone, etc • Includes bones and their associated tissues (cartilage and ligaments) BONE STRUCTURE • Porous and made of proteins and minerals and contains: a) Osteocytes –cells that make bone b) Bone marrow – soft bone tissue that produces platelets and blood cells BONE DEVELOPMENT • Bones develop from cartilage hardening (ossification) JOINTS • Place where two bones meet • Fixed: no movement between bones (ex. skull). • Semimovable: limited movement (i.e. rib cage and vertebrae) • Movable: see your coloring JOINT STRUCTURE • Cartilage between joints for cushion • Ligaments connect joints