Neurotransmitters are chemicals that communicate between nerves. In some ways, neurons are like computers: they receive messages, process those messages, and send out the results as new messages to other cells. In the case of neurons, messages consist of chemicals that interact with the outer surface of the cell membrane. This chemical interaction with the cell membrane causes chemical changes within the receiving neuron. The process in which when chemical massages are constantly being exchanged between neurons is called neurotransmission. A resting neuron has a negative charge. Therefore there are more negative ions inside the axon than outside the axon. However, the fluid outside the axon has a positive charge. Due to the different charges of the outside and inside of the axon, the axon is polarized. When a neuron is “fired”, several events take place to create an electrical impulse called an action potential. This process depolarizes the axon, which changes the electrical charge inside the axon from negative to positive. In response to this action potential, the vesicles group at the “edge” of the axon and release neurotransmitters into the synapse. The neuron is again polarized and at rest, waiting to “fire” anoth
Muscular contractions do not always cause actual movement. A small fraction of the total number of fibers in most muscles are usually contracting. This serves to maintain the posture of a limb and enables the limb to resist passive elongation or stretch. This slight continuous contraction is called muscle tone.
Nervous System Adaptation plays a significant role in exercise development as seen by mental imagery, cross education, and coactivation. The body must establish and modify it’s own neural network before it can strengthen. A weight lifter can improve his workouts by understanding the fundamentals of NSA. The nervous system plays a large role in how a muscle develops. For example Scientists have found that people who visualize their workouts can stimulate a significant amount of muscle growth. Although scientists would not advise solely visualized workouts they do stress the importance of good mental preparation to help physiological adaptation. Another example of how the nervous system effects muscle development is in cross education. When one injures a muscle often times the doctor will tell them to work the opposite uninjured muscle. This action will indirectly stimulate the injured muscle. When a novice weight lifter flexes a muscle, the opposing muscle restricts movement. After working out for a period of time, this misfiring of the neurons will dissipate. This phenomenon is known as coactivation. Also, in synchronization a novice weight lifter’s movements will be shaky until his or her neural ne
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