Skeletal muscle facts for kids
Quick facts for kids Skeletal striated muscle |
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| A top-down view of skeletal muscle | |
| Latin | textus muscularis striatus skeletalis |
| Code | TH H2.00.05.2.00002 |
Skeletal muscle is a form of "striated" (striped) muscle tissue. It is under the voluntary control of the somatic nervous system. Most skeletal muscles are attached to bones by bundles of collagen fibers known as tendons. It is one of three muscle types, the others being cardiac muscle and smooth muscle.
Skeletal muscle is made up of individual muscle cells or myocytes, known as muscle fibres. Muscle fibres do the work when muscles contract. A great deal is known about their structure and how they work. They contract when they get a nerve impulse.
Images for kids
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ATPase staining of a muscle cross section. Type II fibers are dark, due to the alkaline pH of the preparation. In this example, the size of the type II fibers is considerably less than the type I fibers due to denervation atrophy.
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Structure of muscle fibre showing a sarcomere under electron microscope with schematic explanation.
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Diagram of sarcoplasmic reticulum with terminal cisternae and T-tubules.
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Human embryo showing somites labelled as primitive segments.
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When a sarcomere contracts, the Z lines move closer together, and the I band becomes smaller. The A band stays the same width. At full contraction, the thin and thick filaments overlap.
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Contraction in more detail
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(a) Some ATP is stored in a resting muscle. As contraction starts, it is used up in seconds. More ATP is generated from creatine phosphate for about 15 seconds. (b) Each glucose molecule produces two ATP and two molecules of pyruvic acid, which can be used in aerobic respiration or converted to lactic acid. If oxygen is not available, pyruvic acid is converted to lactic acid, which may contribute to muscle fatigue. This occurs during strenuous exercise when high amounts of energy are needed but oxygen cannot be sufficiently delivered to muscle. (c) Aerobic respiration is the breakdown of glucose in the presence of oxygen (O2) to produce carbon dioxide, water, and ATP. Approximately 95 percent of the ATP required for resting or moderately active muscles is provided by aerobic respiration, which takes place in mitochondria.
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Jogging is one form of aerobic exercise.
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In muscular dystrophy, the affected tissues become disorganized and the concentration of dystrophin (green) is greatly reduced.
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Prisoner of war exhibiting muscle loss as a result of malnutrition.
See also
In Spanish: Músculo esquelético para niños
