Answer:
Ion channels in the plasma membrane of the receiving neuron open
Explanation:
Ionotropic receptors are protein structures of the neuronal plasma membrane that function as specific ion channels for certain ions. Depending on the type of ion involved is the nature of the effect that occurs when these channel receptors open. Being ionic channels, these types of receptors participate in the rapid, exciting or inhibitory responses that neurons give.
For now we will refer only to ionotropic excitatory receptors which, by allowing the passage of ions such as sodium or calcium, produce a decrease in membrane potential (hypopolarization). This increases the probability of generating action potentials in the neuron.
To these, like other types of receptors, specific neurotransmitters are attached, which causes their activation and opening.
In addition to presenting an ionic channel in their structure, these receptors have a site where a specific neurotransmitter (binding site to the neurotransmitter) binds. But there are also sites of binding to other molecules, which without causing their opening modify, however, the effect of the neurotransmitter. That is, the receptors can be modulated by other molecules.
A typical example of an ionotropic receptor is the cholinergic receptor (its specific neurotransmitter is acetylcholine, ACh) of the nicotinic subtype found in the skeletal neuromuscular synapse. Part A of the scheme. When ACh binds to the receptor, the channel opens causing sodium ion (Na +) to enter, causing hypopolarization (or depolarization) at that point. The name of this type of receptors derives from the fact that they can be identified with nicotine, a substance that specifically binds to them.
