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What are rodlike structures within skeletal muscles that contain filaments organized into sarcomeres?
Wiki User
∙ 13y ago
myofilaments
Wiki User
∙ 13y ago
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Where are the myosin filaments found?
Myosin and Actin are contractile proteins that make up the sarcomeres, the contractile components of myofibrils, which make up skeletal and cardiac muscle.
What is a myofliament?
The filaments of myofibrils constructed from proteins, myofilaments, consist of 2 types, thick and thin. Thin filaments consist primarily of the protein actin; thick filaments consist primarily of the protein myosin. The protein complex composed of actin and myosin is sometimes referred to as "actomyosin." In striated muscle, such as skeletal and cardiac muscle, the actin and myosin filaments each have a specific and constant length on the order of a few micrometers, far less than the length of the elongated muscle cell (a few millimeters in the case of human skeletal muscle cells). The filaments are organized into repeated subunits along the length of the myofibril. These subunits are called sarcomeres.
How can smooth muscle contract if it has no striation or sarcomeres?
Actin and myosin are present in all three muscle types. In skeletal and cardiac muscle cells, these proteins are organized in sarcomeres, with thin and thick filaments. The internal organization of a smooth muscle cell is very different: • A smooth muscle fibre has no T tubules, and the sarcoplasmic reticulum (SR) forms a loose network throughout the sarcoplasm. Smooth muscle tissue has no myofibrils or sarcomeres. As a result, this tissue also has no striations and is called nonstriated muscle. • Thick filaments are scattered throughout the sarcoplasm of a smooth muscle cell. The myosin proteins are organized differently than in skeletal or cardiac muscle cells, and smooth muscle cells have more cross-bridges per thick filament. • The thin filaments in a smooth muscle cell are attached to dense bodies, structures distributed throughout the sarcoplasm in a network of intermediate filaments composed of the protein desmin. Some of the dense bodies are firmly attached to the sarcolemma. The dense bodies and intermediate filaments anchor the thin filaments such that, when sliding occurs between thin and thick filaments, the cell shortens. Dense bodies are not arranged in straight lines, so when a contraction occurs, the muscle cell twists like a corkscrew. • Adjacent smooth muscle cells are bound together at dense bodies, transmitting the contractile forces from cell to cell throughout the tissue. • Although smooth muscle cells are surrounded by connective tissue, the collagen fibres never unite to form tendons or aponeuroses as they do in skeletal muscles.
What are the repeating segments seen in skeletal muscle fiber?
sarcomeres
Does cardiac muscles have sarcomeres?
Only striated muscles have sarcomeres , Skeletal and Cardiac muscles have sarcomeres. As for smooth muscles they doesnt have sarcomeres , since the Z lines are attached to dense bodies
Do myosin filaments outnumber actin filaments in skeletal muscles?
No. 2 to active
Do skeletal muscle fibers contain sarcomeres whereas smooth muscle fibers do not?
true
What band shortens during skeletal muscle contraction?
during skeletal muscle contraction ,I band and H zone shortens. Sarcomeres
Is Heart made up of striated or non striated muscles?
Heart muscle is striated but not in the same way that skeletal muscle is. Cardiac muscle is a type of involuntary striated muscle found only in the walls of the heart.Cardiac and skeletal muscle are similar in that both appear to be striated in that they contain sarcomeres. In striated muscle, such as skeletal and cardiac muscle, the actin and myosin filaments each have a specific and constant length on the order of a few micrometers, far less than the length of the elongated muscle cell (a few millimeters in the case of human skeletal muscle cells).The filaments are organized into repeated subunits along the length. These subunits are called sarcomeres. The sarcomeres are what give skeletal and cardiac muscles their striated appearance of narrow dark and light bands, because of the parallel arrangement of the actin and myosin filaments.However, cardiac muscle has unique features relative to skeletal muscle. For one, the myocytes are much shorter and are narrower than the skeletal muscle cells, being about 0.1 millimeters long and 0.02 millimeters wide .Furthermore, while skeletal muscles are arranged in regular, parallel bundles, cardiac muscle connects at branching, irregular angles.Anatomically, the muscle fibers are typically branched like a tree branch. In addition, cardiac muscle fibers connect to other cardiac muscle fibers through intercalcated discs and form the appearance of a syncytium (continuous cellular material).These intercalcated discs, which appear as irregularly-spaced dark bands between myocytes, are a unique and prominent feature of cardiac muscle .
The smallest functional unit of the muscle fiber?
The smallest functional unit of a muscle fiber is the sarcomere. Sarcomeres are composed of actin and myosin filaments arranged in a repeating pattern, allowing for muscle contraction and relaxation to occur. They are responsible for the striated appearance of skeletal muscle under a microscope.
What structural protein of skeletal muscle also acts as an enzyme?
Myosin thick filaments
What characteristic striated appearance of skeletal is due to the arrangement of alternating protein filaments composed of?
jill
