(a) Parasympathetic pathway. ACh is released from the preganglionic neuron over the synapse and ...

(a) Parasympathetic pathway. ACh is released from the preganglionic neuron over the synapse and stimulates cholinergic (nicotine) receptors. Then ACh is released from the postganglionic neuron, which activates the cholinergic (muscarinic) receptors on the target tissue. (b) Sympathetic pathway: Acetylcholine (ACh) is released from the preganglionic neuron and stimulates cholinergic (nicotine) receptors on the postganglionic neuron. Then, norepinephrine (NE) is released from the end of the postganglionic neuron, which is then transmitted to the target tissue, where it activates receptors on the surface. These adrenergic (sympathetic) receptors are either alpha (a) or beta (b). (c) Somatic motor pathway: nicotinic receptors on skeletal muscle.