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Animal Systems Muscle System Muscular System Function-- to move the animal about, to provide movement for the proper functioning of the organs. Meat production -- muscles are processed into meat; 30-40% of the animal’s body is muscle. Three types of muscle Skeletal Muscle Movement -- movement for the bones of the skeleton and other voluntary movement; composed of long, striated bundles that contract and relax Tendons -- connect muscles to bones Red Muscle -- contain many mitochondria; lots of blood; contract for long periods of time Skeletal Muscle White Muscle -- Fewer mitochondria; contract faster; fatigue faster. Smooth Muscle Movement -- Controls movements of the internal organs; involuntary; non-striated sheets. Examples-- Digestive tract, urinary tract Cardiac Muscle Movement -- muscles that control the heart; striated and arranged in bands; involuntary; amazing Stamina -- # of times a heart beats in a lifetime? D. List the Three Types of Muscles Skeletal Muscles Attached to bones Voluntary Striated The skeleton and the skeletal muscles function together allowing an animal to move. Skeletal Muscle D. List the Three Types of Muscles In addition to skeletal muscles, other types of muscles include: Smooth muscles Found in blood vessels, digestive tracts, and reproductive tracts Involuntary, Not striated Cardiac muscles Are found in the heart. Involuntary, Striated Smooth Muscle Cardiac Muscle E. Point out how Muscles aid in Movement Vertebrates move by the actions of muscles on bones. Muscles generally work in pairs to produce movement: when one muscle flexes (or contracts) the other relaxes, a process known as antagonism. E. Point out how Muscles aid in Movement The striations with in the muscle cell are thread-like structures called myofibrils. Within each myofibril there are dense lines called Z lines. A sarcomere (or muscle functional unit) extends from Z line to Z line. E. Point out how Muscles aid in Movement Each sarcomere has thick and thin filaments. The thick filaments are made of myosin and occupy the center of each sarcomere. Thin filaments are made of actins and anchor to the Z line. Sarcomere E. Point out how Muscles aid in Movement Muscles contract by shortening each sarcomere. The sliding filament model of muscle contraction has thin filaments on each side of the sarcomere sliding past each other until they meet in the middle. Myosin filaments have club-shaped heads that project toward the actin filaments. Contraction of a Sarcomere E. Point out how Muscles aid in Movement Myosin heads attach to binding sites on the actin filaments. The myosin heads swivel toward the center of the sarcomere, detach and then reattach to the nearest active site of the actin filament. Each cycle of attachment, swiveling, and detachment shortens the sarcomere 1%. Hundreds of such cycles occur each second during muscle contraction.