Explain why the rate of conduction of a nerve impulse is greater in a myelinated axon than in an unmyelinated axon .
解释为什神经脉冲在有髓鞘的轴突传递速率较无髓鞘的轴突为快.
In contrast to white fat , brown fat is richly vascularized and has numerous unmyelinated nerves which provide sympathetic stimulation to the adipocytes .