Biological Systems MCAT Practice Exam 2025 – The Comprehensive All-in-One Guide for Exam Success!

The effect of a neurotransmitter on a neuron is primarily determined by the receptor present on the postsynaptic cell. Different types of neurotransmitters can bind to various subclasses of receptors, each of which can evoke distinct cellular responses. For example, the same neurotransmitter might activate excitatory or inhibitory pathways depending on the receptor type it binds to, such as ionotropic receptors that mediate fast synaptic transmission or metabotropic receptors that influence slower signaling pathways.

While the type of neurotransmitter, the action potential frequency, and the amount of neurotransmitter released can influence neuronal communication, it is the specific receptors on the postsynaptic neuron's membrane that ultimately dictate the physiological response. This illustrates the concept that the same neurotransmitter can produce different effects in different types of neurons or even in the same neuron, depending on the receptor types expressed.