Acetylcholine & noradrenaline

Combined innervation

The sympathetic system influences a wide spectrum of visceral and somatic structures/organs. The parasympathetic system innervates only those visceral structures which receive input from the cranial nerves (e.g. vagal nerve slows the heart rate and increases peristaltic movement).

The parasympathetic system also affects organs in the pelvic region. Organs with dual or double innervation receive input from both systems. Often with opposing actions.


Alzheimer's disease is characterized by a shortage of acetylcholine in the synaptic cleft, or a shortage of acetylcholine neurons. Which of the following drug mechanisms is a potentially useful medicine against Alzheimer's disease?