Final answer:
Once Ach binds to its receptor on the postganglionic fiber, it opens a channel and causes depolarization of the ganglia, leading to the activation of postganglionic fibers and the release of ACh onto the target organ.
Step-by-step explanation:
Once Ach binds to its receptor on the postganglionic fiber, a channel opens to allow positive ions to cross the cell membrane. This results in depolarization of the ganglia, leading to the activation of postganglionic fibers and the release of ACh onto the target organ.
The action potential generated by the depolarization of the postsynaptic membrane triggers various physiological responses in the target organ.