Final answer:
Ligands, which are neurotransmitters, have a distinctive shape that fits into corresponding receptors on the postsynaptic neuron in a specific lock-and-key relationship during neurotransmission. This specificity is critical to the precise signaling between neurons, involving ionotropic and metabotropic receptors.
Step-by-step explanation:
The concept of ligands and receptors explained by the analogy that ligands are to keys as the receptors are to locks refers to the specificity with which neurotransmitters bind to receptors during neurotransmission. This lock-and-key relationship implies that each neurotransmitter, which acts as a ligand, has a distinct shape that corresponds to a particular receptor on the post-synaptic neuron, much like a unique key fits into a specific lock. In this process, neurotransmitters diffusely cross the synaptic cleft to bind with their specific receptors, resulting in the continuation of the neural signal.
There are different types of receptors, ionotropic and metabotropic. Ionotropic receptors are directly linked to ion channels and affect the neuron's electrical state, while metabotropic receptors involve a series of intracellular events that lead to changes within the cell. Understanding this mechanism is critical for grasping how neurons communicate and respond to signals.