muscle fiber

筋線維

WordNet

1. make ones way by force; "He muscled his way into the office"
2. animal tissue consisting predominantly of contractile cells (同)muscular_tissue
3. one of the contractile organs of the body (同)musculus
4. authority or power or force (especially when used in a coercive way); "the senators used their muscle to get the party leader to resign"
5. tell a relatively insignificant lie; "Fibbing is not acceptable, even if you dont call it lying"
6. a trivial lie; "he told a fib about eating his spinach"; "how can I stop my child from telling stories?" (同)story, tale, tarradiddle, taradiddle
7. a slender and greatly elongated substance capable of being spun into yarn (同)fibre
8. a leatherlike material made by compressing layers of paper or cloth (同)fibre, vulcanized fiber
9. any of several elongated, threadlike cells (especially a muscle fiber or a nerve fiber) (同)fibre

PrepTutorEJDIC

1. 〈U〉(動物体の組織としての)『筋肉』,筋(きん);〈C〉(体の各部を動かす)筋肉 / 〈U〉力,(特に)筋力,腕力 / 《俗に》(…に)強引に割り込む《+『in on』(『into, through』)+『名』》
2. (ささいな,罪のない)うそ / 軽いうそをつく
3. 筋肉の,筋力のある / 力ずくの

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/01/20 12:15:48」(JST)

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"Myofiber" redirects here. For protein structures inside cells, see Myofibril.

Overall structure of a muscle cell and neuromuscular junction:
1. Axon
2. Neuromuscular junction
3. Muscle fiber (Myocyte)

4. Myofibril

A myocyte (also known as a muscle cell or muscle fiber) is the type of cell found in muscle tissue. Myocytes are long, tubular cells that develop from myoblasts to form muscles in a process known as myogenesis. There are various specialized forms of myocytes: cardiac, skeletal, and smooth muscle cells, with various properties. Cardiac myocytes are responsible for generating the electrical impulses that control the heart rate, and are centronucleated. Skeletal muscle fibers help support and move the body and tend to have peripheral nuclei. Smooth muscle fibers control involuntary movements such as the peristalsis contractions in the stomach.

Terminology

The unusual microstructure of muscle cells has led cell biologists to create specialized terminology. However, each term specific to muscle cells has a counterpart that is used in the terminology applied to other types of cells:

Muscle cell	Other organismal cells
sarcoplasm	cytoplasm
sarcoplasmic reticulum	smooth endoplasmic reticulum (SER)
sarcosome	mitochondrion
sarcolemma	cell membrane or plasma membrane

Every muscle is surrounded by fascia. Fascia is composed of three layers of connective tissue, the epimysium, perimysium, and endomysium. Each muscle fiber is surrounded by a layer of connective tissue called the endomysium.

The sarcoplasm is the cytoplasm of a muscle fiber. Most of the sarcoplasm is filled with myofibrils, which are long protein cords composed of myofilaments. The sarcoplasm is also composed of glycogen, a polysaccharide of glucose monomers, which provides energy to the cell with heightened exercise, and myoglobin, the red pigment that stores oxygen until needed for muscular activity.

There are three types of myofilaments:

Thick filaments are composed of protein molecules called myosin. In striations of muscle bands, these are the dark filaments that make up the A band.

Thin filaments are composed of protein molecules called actin. In striations of muscle bands, these are the light filaments that make up the I band.

Elastic filaments are composed of titin, a large springy protein; these filaments anchor the thick filaments to the Z disc.

Together, these myofilaments work together to produce a muscle contraction.

The sarcoplasmic reticulum(SR), also known as the smooth endoplasmic reticulum, forms a network around each myofibril of the muscle fiber. This network is composed of groupings of two dilated end-sacs called terminal cisternae, and a single transverse tubule, or T tubule, which bore through the cell and emerge on the other side; together these three components form the triads that exist within the network of the sarcoplasmic reticulum, in which each T tubule has two terminal cisternae on each side of it. The SR serves as reservoir for calcium ions, so when an action potential spreads over the T tubule, it signals the SR to release calcium from the gated membrane channels to stimulate a muscle contraction.

The sarcolemma is the plasma membrane of a muscle fiber and is designed to receive and conduct stimuli. At the end of each muscle fiber, the outer layer of the sarcolemma combines with tendon fibers. Within the muscle fiber pressed against the sarcolemma are multiple flattened nuclei; this multinuclear condition results from multiple myoblasts fusing to produce each muscle fiber where each myoblast contributes one nucleus.

Myofibrils

Main articles: Myofibril and Sarcomere

Portion of a myofibril, showing sarcomere structure:
S = Sarcomere, unit of muscle function
A = A-band, region of myosin
I = I-band, region of actin
H = H-zone, region of just myosin
Z = Z-line, sarcomere boundary

M = M-line, sarcomere center

Each myocyte contains myofibrils, which are very long chains of sarcomeres, the contractile units of the cell. A cell from the biceps brachii muscle may contain 100,000 sarcomeres. The myofibrils of smooth muscle cells are not arranged into sarcomeres. The sarcomeres are composed of thin and thick filaments. Thin filaments are actin filaments, whereas thick filaments consist of an arrangement of myosin proteins. The sarcomere does not contain organelles or a nucleus. Individual myocytes are surrounded by endomysium.

Myocytes are bound together by perimysium into bundles called fascicles; the bundles are then grouped together to form muscle tissue, which is enclosed in a sheath of epimysium. The perimysium contains blood vessels and nerves which provide for the muscle fibers. Muscle spindles are distributed throughout the muscles and provide sensory feedback information to the central nervous system.

Functional control

Kindlin-2 plays a role in elongation.

GATA4 and GATA6 play a role in differentiation.

Myoblasts

A myoblast is a type of embryonic progenitor cell that differentiates to give rise to muscle cells.

Skeletal muscle fibers are made when myoblasts fuse together; muscle fibers therefore have multiple nuclei (each nucleus originating from a single myoblast). The fusion of myoblasts is specific to skeletal muscle (e.g., biceps brachii) and not cardiac muscle or smooth muscle.

Myoblasts that do not form muscle fibers dedifferentiate back into satellite cells. These satellite cells remain adjacent to a muscle fiber, situated between the sarcolemma and the endomysium (the connective tissue investment that divides the muscle fascicles into individual fibers). To re-activate myogenesis, the satellite cells must be stimulated so they differentiate into new fibers.

See also

• Sinoatrial node

References

External links

• Structure of a Muscle Cell

UpToDate Contents

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• 1. 筋肉におけるエネルギー代謝 energy metabolism in muscle
• 2. 神経筋接合部の電気診断学的評価 electrodiagnostic evaluation of the neuromuscular junction
• 3. 筋萎縮性側索硬化症およびその他の運動ニューロン疾患の診断 diagnosis of amyotrophic lateral sclerosis and other forms of motor neuron disease
• 4. HIV感染患者における筋疾患 muscle disease in hiv infected patients
• 5. マハイム束の頻拍 mahaim fiber tachycardias

English Journal

• Overexpression of PGC-1α Increases Fatty Acid Oxidative Capacity of Human Skeletal Muscle Cells.

• Nikoli? N, Rhedin M, Rustan AC, Storlien L, Thoresen GH, Stromstedt M.SourceDepartment of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, N-0316 Oslo, Norway.
• Biochemistry research international.Biochem Res Int.2012;2012:714074. Epub 2011 Sep 4.
• We investigated the effects of PGC-1α (peroxisome proliferator-activated receptor γ coactivator-1α) overexpression on the oxidative capacity of human skeletal muscle cells ex vivo. PGC-1α overexpression increased the oxidation rate of palmitic acid and mRNA expression of genes regulating lipid m
• PMID 21904680

Japanese Journal

• Nanoparticle-mediated intracellular lipid accumulation during C2C12 cell differentiation

• Tsukahara Tamotsu,Haniu Hisao
• BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 406(4), 558-563, 2011-03-25
• … In this report, we sought to elucidate whether multiwall carbon nanotubes are involved in the modulation of the proliferation and differentiation of the skeletal muscle cell line C2C12. … Skeletal muscle is a major mass peripheral tissue that accounts for 40% of total body weight and 50% of energy consumption. … We focused on the differentiation pathway of myoblasts after exposure to a vapor-grown carbon fiber, HTT2800, which is one of the most highly purified carbon nanotubes. …
• NAID 120003020569

Related Links

• Skeletal striated muscle - Wikipedia, the free encyclopedia

Individual muscle fibers are formed during development from the fusion of several undifferentiated immature cells known as myoblasts into long, cylindrical, multi-nucleated cells. Differentiation into this state is ...

Related Pictures

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★リンクテーブル★

リンク元	「skeletal myocyte」「筋線維」「muscle fibre」「筋繊維」
拡張検索	「cardiac muscle fiber」
関連記事	「muscle」

「skeletal myocyte」

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• 骨格筋細胞

関

muscle fiber、myotube、skeletal muscle cell

「筋線維」

　　[★]

英

muscle fiber (K)

同

筋細胞 muscle cell

関

筋肉

「muscle fibre」

　　[★]

筋線維、筋繊維

関

muscle fiber、myofiber

「筋繊維」

　　[★]

英

[[]]

同

muscle fiber

関

[[]]

同

muscle fiber

「cardiac muscle fiber」

　　[★]

• 心筋線維

関

cardiac fiber

「muscle」

　　[★]

• n.

• 筋肉