In the sympathetic system, acetylcholine is used at preganglionic to postganglionic synapses, and postganglionic to effector synapses occur only sometimes.

In the sympathetic system, acetylcholine is used at preganglionic to postganglionic synapses, and postganglionic to effector synapses occur only sometimes.

• A. It is released from preganglionic to postganglionic neurons, and from postganglionic to effectors only sometimes.
• B. It is released from preganglionic to postganglionic neurons, and from postganglionic to effectors always.
• C. It is released only from postganglionic neurons to effectors.
• D. It is never used.

Answer: (A)

The important idea is how neurotransmitters are used in the sympathetic division. Preganglionic neurons always release acetylcholine onto nicotinic receptors on the postganglionic neuron, so acetylcholine is used at that first synapse. After that, the postganglionic neuron commonly releases norepinephrine onto the target organ to produce the sympathetic effects. However, there is a notable exception: some postganglionic sympathetic fibers release acetylcholine instead of norepinephrine, most famously those that innervate sweat glands, where acetylcholine acts on muscarinic receptors. So the statement is accurate: acetylcholine is used at the preganglionic to postganglionic junction, and its release from postganglionic to effectors occurs only for certain targets.

The important idea is how neurotransmitters are used in the sympathetic division. Preganglionic neurons always release acetylcholine onto nicotinic receptors on the postganglionic neuron, so acetylcholine is used at that first synapse. After that, the postganglionic neuron commonly releases norepinephrine onto the target organ to produce the sympathetic effects. However, there is a notable exception: some postganglionic sympathetic fibers release acetylcholine instead of norepinephrine, most famously those that innervate sweat glands, where acetylcholine acts on muscarinic receptors. So the statement is accurate: acetylcholine is used at the preganglionic to postganglionic junction, and its release from postganglionic to effectors occurs only for certain targets.