State that synapses ensure that impulses travel in one direction only

Synapses ensure that impulses travel in one direction only due to the specific arrangement and function of neurotransmitter release and receptor binding.

Key Points:

1. Unidirectional Transmission: In a chemical synapse, the impulse travels from the presynaptic neuron (the neuron sending the signal) to the postsynaptic neuron (the neuron receiving the signal). This is primarily because neurotransmitters are released from the axon terminals of the presynaptic neuron and bind to receptors on the dendrites of the postsynaptic neuron, creating a one-way flow of information.
2. Neurotransmitter Release: The neurotransmitters are stored in vesicles at the presynaptic terminal and are released into the synaptic cleft when an action potential reaches this terminal. The release occurs exclusively at this site, meaning that there are no receptors for these neurotransmitters on the axon of the presynaptic neuron .
3. Receptor Binding: The postsynaptic neuron has specific receptors that are designed to bind with the released neurotransmitters. This binding initiates a response in the postsynaptic neuron, which can lead to depolarization and potentially trigger a new action potential.
4. Absence of Receptors on Axon Terminals: The presynaptic neuron’s axon terminals do not have neurotransmitter receptors, which prevents any backward transmission of impulses. This anatomical arrangement reinforces the unidirectional nature of synaptic transmission