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Multiple Choice
The narrow space between the synaptic terminal and the muscle fiber is the:
A
myelin sheath
B
sarcomere
C
axon hillock
D
synaptic cleft
Verified step by step guidance
1
Understand the context: The question is asking about the narrow space between the synaptic terminal and the muscle fiber, which is part of the neuromuscular junction where nerve signals are transmitted to muscle fibers.
Review the anatomy of the neuromuscular junction: The synaptic terminal is the end of a motor neuron, and it releases neurotransmitters to communicate with the muscle fiber. The muscle fiber has receptors to receive these signals.
Define the term 'synaptic cleft': The synaptic cleft is the small gap or space between the synaptic terminal of the neuron and the muscle fiber. This gap allows neurotransmitters to diffuse across and bind to receptors on the muscle fiber.
Eliminate incorrect options: The myelin sheath is a protective covering around axons, not part of the synaptic terminal. The sarcomere is the functional unit of muscle contraction, unrelated to the synaptic cleft. The axon hillock is the part of the neuron where action potentials are initiated, not involved in the synaptic cleft.
Conclude that the correct answer is 'synaptic cleft,' as it specifically refers to the narrow space where neurotransmitter communication occurs between the neuron and muscle fiber.