Copyright Pearson Prentice Hall Biology Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 36–2 The Muscular System Photo Credit: © Getty Images Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Learning Objectives: What is the main function of the muscular system? What are the 3 types of muscle? Describe and identify the 3 types of muscle. Understand how myosin and actin work within a muscle. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Learning Objectives: 5. Explain how a muscle contracts. 6. Describe what a tendon is and how it is used. 7. Identify flexor and extensor muscles. 8. Explain why exercise improves our muscular system. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscles The function of the muscular system is movement. Muscle makes up more than 40% of your mass. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Types of Muscle Tissue Types of Muscle Tissue What are the three types of muscle tissue? Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Types of Muscle Tissue There are three different types of muscle tissue: skeletal smooth cardiac Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Types of Muscle Tissue Skeletal Muscles Skeletal muscles: are usually attached to bones. are responsible for voluntary movements. have many nuclei. are sometimes called striated muscles. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Types of Muscle Tissue Skeletal Muscles: Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Types of Muscle Tissue Smooth Muscles Smooth muscles: are usually not under voluntary control. are spindle-shaped. have one nucleus. are not striated. are found in many internal organs and blood vessels. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Types of Muscle Tissue Smooth Muscles: Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Types of Muscle Tissue Cardiac Muscle Cardiac muscle: is only found in the heart. is striated. may have one or two nuclei. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Types of Muscle Tissue Cardiac Muscle: Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscle Contraction Muscle Contraction The fibers in skeletal muscles are composed of smaller structures called myofibrils. Each myofibril has smaller structures called filaments. The thick filaments contain a protein called myosin. The thin filaments contain a protein called actin. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscle Contraction Filaments are arranged along the muscle fiber in units called sarcomeres. Sarcomeres are separated by regions called Z lines. When a muscle is relaxed, there are no thin filaments in the center of a sarcomere. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscle Contraction Actin Skeletal muscle Myosin Bundle of muscle fibers Sarcomere Z line Skeletal muscles are made up of bundles of muscle fibers, which in turn are composed of myofibrils. Each myofibril contains thin filaments made of actin and thick filaments made of myosin. Muscle fibers are divided into functional units called sarcomeres. Myofibril Muscle fiber (cell) Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscle Contraction How do muscles contract? Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscle Contraction A muscle contracts when the thin filaments in the muscle fiber slide over the thick filaments. This process is called the sliding filament model of muscle contraction. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscle Contraction During muscle contraction, the actin filaments slide over the myosin filaments, decreasing the distance between the Z lines. During muscle contraction, the actin filaments slide over the myosin filaments, decreasing the distance between the Z lines. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscle Contraction Movement of Actin Filament Actin Cross-bridge Binding sites Myosin During muscle contraction, the actin filaments slide over the myosin filaments, decreasing the distance between the Z lines. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscle Contraction During muscle contraction, the head of a myosin filament attaches to a binding site on actin, forming a cross-bridge. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscle Contraction Powered by ATP, the myosin cross-bridge changes shape and pulls the actin filament toward the center of the sarcomere. Powered by ATP. The myosin cross-bridge changes shape and pulls the actin filament toward the center of the sacromere. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscle Contraction The cross-bridge is broken, the myosin binds to another site on the actin filament, and the cycle begins again. The cross-bridge is broken, the myosin binds to another site on the actin filament, and the cycle begins again. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Muscle Contraction When many myosin cross-bridges change shape in a fraction of a second, the muscle fiber shortens with considerable force. The energy for muscle contraction is supplied by ATP. Copyright Pearson Prentice Hall
Control of Muscle Contraction Impulses from motor neurons control the contraction of skeletal muscle fibers. A neuromuscular junction is the point of contact between a motor neuron and a skeletal muscle cell. Copyright Pearson Prentice Hall
Control of Muscle Contraction Vesicles in the axon terminals of the motor neuron release a neurotransmitter called acetylcholine. Acetylcholine produce an impulse in the cell membrane of the muscle fiber. Copyright Pearson Prentice Hall
Control of Muscle Contraction The impulse causes the release of calcium ions within the fiber. The calcium ions affect regulatory proteins that allow actin and myosin filaments to interact. Copyright Pearson Prentice Hall
Control of Muscle Contraction A muscle cell remains contracted until the release of acetylcholine stops and an enzyme produced at the axon terminal destroys any remaining acetylcholine. Then, the cell pumps calcium ions back into storage, the cross-bridges stop forming, and contraction ends. Copyright Pearson Prentice Hall
How Muscles and Bones Interact Skeletal muscles are joined to bones by tendons. Tendons pull on the bones so they work like levers. The joint functions as a fulcrum. The muscles provide the force to move the lever. Copyright Pearson Prentice Hall
How Muscles and Bones Interact Opposing Muscles Contract and Relax By contracting and relaxing, the triceps and biceps in the upper arm enable you to bend or straighten your elbow. Copyright Pearson Prentice Hall
How Muscles and Bones Interact Opposing Muscles Contract and Relax By contracting and relaxing, the triceps and biceps in the upper arm enable you to bend or straighten your elbow. Copyright Pearson Prentice Hall
How Muscles and Bones Interact Antagonistic pairs: Flexors and Extensors Copyright Pearson Prentice Hall
How Muscles and Bones Interact Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Exercise and Health Exercise and Health Why is exercise important? Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Exercise and Health Regular exercise is important in maintaining muscular strength and flexibility. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Exercise and Health Aerobic exercises help the body’s systems to become more efficient. Resistance exercises increase muscle size and strength. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 36–2 Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 36–2 Skeletal muscles are joined to bones by tough connective tissue called ligaments. tendons. filaments. bursae. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 36–2 Muscle cells that are large, have many nuclei, and striations are skeletal muscle cells. smooth muscle cells. cardiac muscle cells. involuntary muscle cells. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 36–2 Muscle that is found in the walls of blood vessels and intestines is skeletal muscle. smooth muscle. cardiac muscle. striated muscle. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 36–2 The filaments found in skeletal muscle cells are actin and myosin myosin and myofibrils actin and Z lines actin and sarcomeres Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 36–2 The type of muscle found only in the heart is skeletal muscle. striated muscle. cardiac muscle. smooth muscle. Copyright Pearson Prentice Hall
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