List five ways that efferent motor pathways can be distinguished from autonomic pathways

Question

What will be an ideal response?

Answer 1

Answer: Efferent motor neurons control only one type of effector organ-skeletal muscle. Autonomic pathways control many organs. The cell bodies of motor neurons are located in the CNS, never in ganglia outside the CNS. Efferent motor pathways are monosynaptic, meaning that there is only a single synapse between the CNS and the skeletal muscle. This means that efferent motor neurons can be very long. Autonomic pathways are polysynaptic. Synapse morphology is different between autonomic and motor pathways. At the neuromuscular junction, a motor neuron splits into a cluster of axon terminals that branch out over the motor end plate. Autonomic neurons have several synaptic varicosities arranged in series like a string of beads. The size of the synaptic cleft is different. The synaptic cleft between the motor neuron and the muscle is much narrower than that between autonomic neurons and their effector cells. The nature of the neurotransmitter is different. All vertebrate motor neurons release acetylcholine at the neuromuscular junction, whereas sympathetic neurons release epinephrine and parasympathetic neurons release acetylcholine. The response of the effector organ differs. The effect of acetylcholine on skeletal muscle is always excitatory, whereas autonomic neurons may be excitatory or inhibitory.