Question

You smell smoke. Your brain sends action potentials down your spinal cord and preganglionic axons all the way to their ganglia. When the signals reach the synapses in the ganglia, the nerve fibers release a neurotransmitter called _______________________________ (ACh)

Answer 1

ACh is the neurotransmitter released from preganglionic fibers that activates ganglionic neurons in the autonomic system. It binds to nicotinic receptors on these neurons, causing depolarization. Nicotine acts as an ACh analog and activates ganglionic neurons when it binds to ACh receptors.

Step-by-step explanation:

All ganglionic neurons of the autonomic system, in both sympathetic and parasympathetic ganglia, are activated by acetylcholine (ACh) released from preganglionic fibers. The ACh receptors on these neurons are of the nicotinic type, meaning that they are ligand-gated ion channels. When the neurotransmitter released from the preganglionic fiber binds to the receptor protein, a channel opens to allow positive ions to cross the cell membrane. The result is depolarization of the ganglia. Nicotine acts as an ACh analog at these synapses, so when someone takes in the drug, it binds to these ACh receptors and activates the ganglionic neurons, causing them to depolarize.