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Neurons whose axons leave the ventral surface of the brain stem and the spinal cord to convey signals away from the central nervous system are efferent neurons or motor neurons, and these neurons exercise ______ control
motor
They have radii of 0.05–0.6 μm and a conduction speed of u (in m/s) ≈ 1.8√𝑎 where a is the radius of the axon (in μm). Myelinated fibers have outer radii of 0.5–10 μm and a conduction speed of u (in m/s) ≈ 12(a + b) ≈ 17a, where b is the myelin sheath thickness (in μm) (and a + b is the total axon radius). The spacing between the nodes of Ranvier is ≈280a
$u (in m/s) ≈ 1.8\sqrt{a}$ and $u (in m/s) ≈ 12(a + b) ≈ 17a$
There are approximately 10 million afferent neurons, 100 billion neurons in the brain with 100 trillion synapses, and half a million efferent neurons. Bundles of these neuron axons are called ______ outside of the brain and tracts inside the brain
nerves
Approximately 2/3 of the axon fibers in the body are ______
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Neurons whose axons travel from sensing areas to the spinal cord are called afferent neurons or input or ______ neurons
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