muscoskeletal system.docx

Allows calcium ions to enter the axon note that

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allows calcium ions to enter the axon (note that calcium also has an important role here). The calcium ions stimulate the neuron into releasing acetylcholine in the synapse. Acetylcholine then binds to special receptors on the outer surface of the sarcolemma; the permeability of this membrane is altered and an action potential is created. The depolarization is then transmitted along the sarcolemma to the sarcoplasmic reticulum, which then releases calcium ions which cause the sarcomere to contract. The Musculoskeletal System Review - Image Diversity: neuromuscular junction 26. To increase the force of a muscle, is the intensity of muscle contraction increased?
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An increase in the strength of a muscle is not achieved by an increase in the intensity of the stimulation of each muscle fiber. The muscle fiber obeys an all-or-nothing rule, meaning that its contraction strength is only one and cannot be increased. When the body needs to increase the strength of a muscle, a phenomenon known as spatial summation occurs: new muscle fibers are recruited in addition to the fibers already in action. Therefore, the strength of the muscle contraction increases only when the number of active muscle cells increases. 27. What is the difference between the spatial summation and temporal summation of muscle fibers? What is tetany? Spatial summation is the recruiting of new muscle fibers to increase muscle strength. Temporal summation occurs when a muscle fiber is continuously stimulated to contract without being able to go through relaxation. When a muscle fiber remains in a continuous state of contraction via temporal summation, it is known as tetany (this is the clinical condition of patients contaminated by the toxin of tetanus bacteria). Tetany ends when all available energy for contraction is spent or when the stimulus ceases.
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