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Do skeletal muscle fibers contain sarcomeres whereas smooth muscle fibers do not?
Yes, skeletal muscle fibers contain sarcomeres, which are the repeating units responsible for muscle contractions. In contrast, smooth muscle fibers do not have sarcomeres in the same organized structure but still have contractile proteins.
Do smooth muscle cells lack striations?
Yes, smooth muscle cells lack the striations seen in skeletal and cardiac muscle cells. Instead, smooth muscle cells have a more uniform appearance under the microscope due to the absence of organized sarcomeres.
What gives muscle fibers their striations?
The striations in muscle fibers are caused by the arrangement of contractile proteins within the fibers. These proteins, primarily actin and myosin, overlap and interlock in a regular pattern, giving the muscle fibers a striped appearance when viewed under a microscope.
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.
The giant protein titin maintains the organizations of the?
The giant protein titin maintains the organization of sarcomeres in striated muscle cells. Sarcomeres are the basic contractile units of muscle cells and are responsible for muscle contractions. Titin provides structural support and stability to sarcomeres during muscle contraction and relaxation.
What muscle tissue type do not contain sarcomeres?
Smooth.
Do skeletal muscle fibers contain sarcomeres whereas smooth muscle fibers do not?
Yes, skeletal muscle fibers contain sarcomeres, which are the repeating units responsible for muscle contractions. In contrast, smooth muscle fibers do not have sarcomeres in the same organized structure but still have contractile proteins.
Does smooth muscle have z lines?
No, smooth muscle is poorly organized and do not have the Z lines which are characteristic of sarcomeres.
What muscle types has only one nucleus no sarcomeres and rare gap junctions?
Multi-unit Smooth Muscle.
Do smooth muscle cells posses central nuclei but lack striations?
Smooth muscle is not striated, hence the name smooth muscle.nonotcardiac muscle
Do smooth muscle cells lack striations?
Yes, smooth muscle cells lack the striations seen in skeletal and cardiac muscle cells. Instead, smooth muscle cells have a more uniform appearance under the microscope due to the absence of organized sarcomeres.
What is the functional unit of muscle?
sarcomeres
Smooth muscle contractions occurs without the regular rearrangement of what?
Smooth muscle contractions occur without the regular rearrangement of sarcomeres, which are the structural units found in skeletal and cardiac muscle. Instead of organized sarcomeres, smooth muscle fibers have a more dispersed arrangement of actin and myosin filaments, allowing for a more sustained and rhythmic contraction. This unique structure enables smooth muscle to maintain tension over extended periods and adapt to various physiological demands.
What does a muscle do so the sarcomeres shortens?
The sarcomeres shortens when the muscle contract. By Adam Safi
What gives muscle fibers their striations?
The striations in muscle fibers are caused by the arrangement of contractile proteins within the fibers. These proteins, primarily actin and myosin, overlap and interlock in a regular pattern, giving the muscle fibers a striped appearance when viewed under a microscope.
Is tropomyosin found in smooth muscle?
smooth muscle doesn't have troponin, instead it has caldmodulin
Name given to contracting units of muscle fibers?
The name given to contracting units of muscle fibers is sarcomeres. Sarcomeres are the basic functional units of skeletal muscles and they contain overlapping thick and thin filaments that slide past each other during muscle contraction.
