Final answer:
An unmyelinated neuron is slower than a myelinated neuron due to the lack of myelin sheath that facilitates faster impulse transmission via saltatory conduction. Motor, sensory, and interneurons are not inherently slower but depend on whether they are myelinated. The myelin sheath is created by glial cells, not the neurons themselves.
Step-by-step explanation:
The correct answer to the question of which type of neuron is slower than a myelinated neuron is an unmyelinated neuron. This is because the myelin sheath provides an insulating layer that allows for faster transmission of nerve impulses along the axon. Myelinated neurons can transmit impulses more quickly due to the process of saltatory conduction where the electrical signal 'jumps' from one node of Ranvier to the next.
An unmyelinated neuron, lacking this sheath, must propagate the action potential continuously along the entire length of the axon, thus conducting impulses more slowly.
Distinguishing among different types of neurons: Motor neurons convey impulses from the central nervous system to muscles or glands, sensory neurons carry information from sensory receptors to the central nervous system, and interneurons serve as connectors between sensory and motor neurons within the central nervous system. None of these other types of neurons are inherently slower due to the presence or absence of myelin, but rather their speed is influenced by whether they are myelinated or not.
The myelin sheath is not made by the neurons themselves but by supportive (glial) cells: In the central nervous system (CNS), oligodendrocytes form the myelin sheath, whereas in the peripheral nervous system (PNS), Schwann cells perform this function. The transmission of nerve impulses across neurons occurs at the synapse where neurotransmitters released by the presynaptic neuron cross the synaptic gap and bind to receptors on the postsynaptic neuron.