(a) The neuron which connects sense organs aw’ brain is called afferent neuron. The neuron which connects brain and effector organs or the concerned peripheral tissues organs is called efferent neuron.
(b) In a myelinated neuron, impulse is transmitted by chemical method. It allows fast, saltatory movement of action potentials from node to node. In an unmyelinated neuron, impulse is transmitted by clerical mechanism. The conduction velocity of myelinated neurons vary linearly with axon diameter, whereas the speed of unmyelinated neurons vary roughly as the square root of the diameter of axons. Myelinated axon conduction is fast and energy efficient.
