One motor unit obeys a principle called the all-or-none law.Group startsTrue or FalseTrue, unselectedFalse, unselectedGroup ends

Answer: True

The statement "One motor unit obeys a principle called the all-or-none law" is true. The all-or-none law refers to the principle that a neuron or muscle fiber will either fire completely or not at all in response to a stimulus. In the context of motor units, which are comprised of a single motor neuron and the muscle fibers it innervates, the muscle fibers contract fully when stimulated above a certain threshold. If the stimulus is below this threshold, there will be no contraction. This law ensures that muscle contractions are consistent and reliable, allowing for proper motor function.

In practical terms, when a motor neuron sends a signal (action potential) to its associated muscle fibers, all of those fibers will respond with maximum contraction if the signal is strong enough. Conversely, if the signal is too weak, the fibers will not contract at all. This all-or-none response is critical for coordinated movement and muscle performance, as it prevents partial contractions that could lead to inefficiencies or injuries.