what are myofibrils and myofilaments?
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Myofibrils are composed of long proteins including actin, myosin, and titin, and other proteins that hold them together. These proteins are organized into thick and thin filaments called myofilaments, which repeat along the length of the myofibril in sections called sarcomeres.
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Energy Supply for Muscle Contraction. Energy for the release and movement of the myosin head along the actin filament comes from adenosine triphosphate (ATP). Recall from the sliding filament theory that the actin and myosin chains slide past one another. The binding of ATP allows the myosin heads to detach from actin.
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All muscle cells share several properties: contractility, excitability, extensibility, and elasticity: Contractility is the ability of muscle cells to forcefully shorten.
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Each fascicle is surrounded by another layer of connective tissue termed the endomysium. Skeletal muscle tissue is composed of numerous muscle fibers which are separated from adjacent muscles and other tissues by a layer of dense, elastic connective tissue termed the fascia.
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Muscle tissue contains something called muscle fibers. Muscle fibers consist of a single muscle cell. They help to control the physical forces within the body. When grouped together, they can facilitate organized movement of your limbs and tissues.
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Gills are tissues that are like short threads, protein structures called filaments. These filaments have many functions including the transfer of ions and water, as well as the exchange of oxygen, carbon dioxide, acids and ammonia.
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A myocyte (also known as a muscle cell) is the type of cell found in some types of muscle tissue. Myocytes develop from myoblasts to form muscles in a process known as myogenesis. ... On the other hand, skeletal muscles are formed by morphological units referred to as muscle fibers.
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A muscle fascicle is a bundle of skeletal muscle fibers surrounded by perimysium, a type of connective tissue. (There is also a nerve fascicle of axons.)
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Thick myofilaments are comprised of around 300 spirally arranged protein molecules called myosin. Each myosin molecule is composed of two heavy chains and four light chains.
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The basic histologic component of all skeletal muscles is the skeletal muscle cells, also known as muscle fibers or myofibers. Myofibers are grouped into larger units called muscle fascicles, which are enveloped together by connective tissue (called epimysium) into anatomically recognized muscles.
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A muscle fascicle is a bundle of skeletal muscle fibers surrounded by perimysium, a type of connective tissue.
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['Structural proteins: e.g. the collagen, the fibrillins, and elastin.', 'Specialized proteins: e.g. fibronectin, the various laminins, and the various integrins.']
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All muscles are made of a kind of elastic tissue. Each muscle consists of thousands, or tens of thousands, of small musculus fibers. Each muscle fiber is about 40 millimeters long. It consists of tiny strands of fibrils.
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['Epimysium - Outermost layer. Surrounds the entire muscle.', 'Perimysium - Surrounds groups of muscle fibers called fascicles.', 'Endomysium - Deepest layer. Separates individual muscle fibers.']
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Thick filaments consist primarily of the protein myosin. Each thick filament is approximately 15 nm in diameter, and each is made of several hundred molecules of myosin. A myosin molecule is shaped like a golf club, with a tail formed of two intertwined chains and a double globular head projecting from it at an angle.
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Although they do not have striations and sarcomeres, smooth muscle fibers do have actin and myosin contractile proteins, and thick and thin filaments. These thin filaments are anchored by dense bodies. A dense body is analogous to the Z-discs of skeletal and cardiac muscle fibers and is fastened to the sarcolemma.
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Three broad classes of muscle fibers exist: skeletal, cardiac and smooth. Skeletal muscle fibers are multi-nucleated long fibers that have a cross striated outer appearance under a microscope (1).