Search results
Results from the WOW.Com Content Network
Myofibrils are composed of long proteins including actin, myosin, and titin, and other proteins that hold them together. These proteins are organized into thick , thin , and elastic myofilaments , which repeat along the length of the myofibril in sections or units of contraction called sarcomeres .
The weakened contractile function of skeletal muscle is also linked to the state of the myofibrils. Recent studies suggest that these conditions are associated with altered single fiber performance due to decreased expression of myofilament proteins and/or changes in myosin-actin cross-bridge interactions.
Muscle cells develop from embryonic precursor cells called myoblasts. [1] Skeletal muscle cells form by fusion of myoblasts to produce multinucleated cells in a process known as myogenesis. [4] [5] Skeletal muscle cells and cardiac muscle cells both contain myofibrils and sarcomeres and form a striated muscle tissue. [6]
Skeletal muscles are composed of tubular muscle cells (called muscle fibers or myofibers) which are formed during embryonic myogenesis. Muscle fibers contain numerous tubular myofibrils. Myofibrils are composed of repeating sections of sarcomeres, which appear under the microscope as alternating dark and light bands.
The sarcoplasmic reticulum surrounds the myofibrils and holds a reserve of the calcium ions needed to cause a muscle contraction. Periodically, it has dilated end sacs known as terminal cisternae. These cross the muscle fiber from one side to the other. In between two terminal cisternae is a tubular infolding called a transverse tubule (T tubule).
The functional unit of a muscle fiber is called a sarcomere. [2] Each muscle cell contains myofibrils composed of actin and myosin myofilaments repeated as a sarcomere. [ 3 ] Many nuclei are present in each muscle cell placed at regular intervals beneath the sarcolemma.
It contains mostly myofibrils (which are composed of sarcomeres), but its contents are otherwise comparable to those of the cytoplasm of other cells. It has a Golgi apparatus near the nucleus , mitochondria just inside the cell membrane ( sarcolemma ), and a smooth endoplasmic reticulum (specialized for muscle function and called the ...
Skeletal muscle, is a type of striated muscle, composed of muscle cells, called muscle fibers, which are in turn composed of myofibrils. Myofibrils are composed of sarcomeres, the basic building blocks of striated muscle tissue.