Autonomic motor pathways are organized as which of the following?

Autonomic motor pathways are organized as which of the following?

• A. A single neuron from the CNS directly to the effector organ.
• B. A three-neuron chain with a preganglionic neuron in the CNS, a postganglionic neuron in a peripheral ganglion, and an effector neuron.
• C. Two-neuron chain with a preganglionic neuron in the CNS and a postganglionic neuron in a peripheral ganglion.
• D. Two-neuron chain with a preganglionic neuron in the CNS and a postganglionic neuron in a peripheral ganglion.

Answer: (D)

Autonomic motor pathways use a two-neuron relay. A preganglionic neuron, with its cell body in the CNS, sends a myelinated axon to a peripheral autonomic ganglion and synapses on a postganglionic neuron located there. The postganglionic neuron then sends an unmyelinated axon to the target organ, such as smooth muscle, cardiac muscle, or a gland. This arrangement allows the CNS to regulate peripheral targets through a single relay station in the peripheral ganglion, rather than a direct one-neuron path. The sympathetic division also has the option of the adrenal medulla, where the preganglionic neuron stimulates chromaffin cells to release hormones into the bloodstream, but the basic organizational principle remains a two-neuron chain with a peripheral ganglion in between.

Autonomic motor pathways use a two-neuron relay. A preganglionic neuron, with its cell body in the CNS, sends a myelinated axon to a peripheral autonomic ganglion and synapses on a postganglionic neuron located there. The postganglionic neuron then sends an unmyelinated axon to the target organ, such as smooth muscle, cardiac muscle, or a gland. This arrangement allows the CNS to regulate peripheral targets through a single relay station in the peripheral ganglion, rather than a direct one-neuron path. The sympathetic division also has the option of the adrenal medulla, where the preganglionic neuron stimulates chromaffin cells to release hormones into the bloodstream, but the basic organizational principle remains a two-neuron chain with a peripheral ganglion in between.