What is the motor unit?
The motor unit consists of one alpha motor neuron along with all muscle fibers that stimulate. Because the human body contains an average of 250,000,000 muscle cells and approximately 420,000 motor neurons, the motor unit will generally consist of a single motor neuron paired with many muscle fibers. In strength training with increasing the early strength, which is observed by newcomers, often do not obtain the size or number of muscle fibers, but activation of motor units that were previously sleeping. Neurons usually consist of a cell body - axon - and dendrites. If the neuron should be considered a tree, axon would be analogous to the trunk and dendrites on the branches. Neurons found in the brain usually have relatively short axons, but neurons that are part of the motor unit - because they have to connect the muscles of the body - have elongaxons that pass through the spinal cord and out into the associated muscle fibers. Each muscle fiber is associated with a particular dendrit and through a dendRites are transmitted between the central nervous system and the muscle fiber.
Muscle fibers are an extended cell, specialized in performing the functions of specific muscles that include part of which are included. This is true of heart heart muscles, smooth muscles that form the lining of many internal organs and skeletal muscles. However, only skeletal muscles are under conscious control. The size and shape of the muscle fiber depends on its function, with smooth muscle cells flattened and similar to the tile; skeletal muscle cells, long and a rope similar; and heart muscle cells that have certain two other two.
The only muscle usually consists of a series of motor units of working, known as the motor pool . If the central nervous system requires it to happen muscle, an electrical signal is sent along the motor neuron that stimulates muscle fibers for download. For everyoneThe contraction is followed by a brief time of relaxation of muscle fibers and this formula is repeated in a wave similar to a wave known as a twitch. The skeletal muscle fibers can be divided into slow twitching and rapid twitching, depending on the length of time required for contraction and relaxation. The famous Twitch fibers are associated with endurance, while fast muscle fibers are associated with power.
individuals may have a predominance of one type of muscle fibers or the other or a combination of these two. All muscle fibers in the motor unit will have a single type, which means either rapid twitching or slow jerking. This may include up to 1,000 muscle fibers, as in the large quadriceps thigh muscles, or less than ten, as seen in motor units of a high degree of accuracy, such as the muscles that control the movement of the eyes.
After contraction, the smallest motor unit, ie one associated with the smallest muscle fibers, is usually the first activated. As the contractions progresses, the game is put into the gamemore engine units. Effective muscle contractions depend on motor units in muscle that work effectively. Regular physical training makes this kind of coordination easier.
Sometimes the motor unit receives a series of fast contractual stimulations in such a rapid succession that the motor fund does not have time to enter the relaxation phase of each jerk. If this happens, it can be guided to the state of maximum contraction, known as tetanic contraction . A significantly stronger than natural twitching can result from a number of causes such as disease or adverse reaction of the drug. One of the most famous reasons for this phenomenon is associated with tetanemfection.