Membrane receptors at a synapse are ligand-gated ion channels that open and allow sodium ions to flow into the neuron upon binding of the neurotransmitter ligand to generate an action potential in the neuron.
Neurotransmitters diffuse across the synaptic cleft (a very short distance) and bind to receptor proteins on the postsynaptic membrane. Excitatory neurotransmitters cause sodium ions to move through receptor proteins depolarizing the membrane. Inhibitory neurotransmitters do not depolarize the postsynaptic membrane. Thus, the condition that would produce inhibition at synapse is called HYPERPOLARIZATION.
Synapse? Dendrite? Dendritic spine? Or, "You could maybe a better answer to your question get if you re-stated it less confusingly as?" ie, perhaps, "Where are the receptor sites involved in transmitting a nerve impulse LOCATED?"
Synapse
The space between two neurons or between a neuron and a receptor is known as a synapse. In this gap, neurotransmitters are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron, allowing for communication between the two cells.
Chemical Synapse
All neurons'impulsestravel to the synapse of the neuron. The synapse is the end of the neuron where theimpulsecantravelto another neuron or the any other receptor cell in the body.
The effect of the drug ecstasy causes a build up of serotonin at the synapse gap. This is because the ecstasy causes a blockage at the receptor molecules, meaning the synapse chemicals (serotonin), are unable to be 'absorbed' by the receptor molecules.
An action potential (or impulse, if you like) reaches the "presynaptic knob". This causes calcium gates in the membrane to open, and an there is an influx of calcium ions into the axon. this causes vesicles (like little sacks) containing transmitter substance, to move towards, and fuse with, the synaptic membrane. this causes the transmitter substance to diffuse across the membrane, where it combines with specfic receptor proteins on the post synaptic membrane. These cause an increased permeability in the membrane to sodium ions, and these rush in. if the threshold value was reached, the influx of NA+ ions will be sufficient to cause an action potential / impulse, and the impulse will travel down the axon.
It can be an excitatory postsynaptic potential (EPSP) or an inhibitory postsynaptic potential (IPSP), depending on the synapse. The EPSP depolarizes the membrane, while the IPSP hyperpolarizes it.
When a nerve is stimulated, its cell membrane is depolarised so that the inside of the cell becomes less negative. The potential is conducted along the axon to the axon terminal. At the dendrite it stimulates the release of a chemical transmitter, which diffuses across a synapse. The transmitter binds to receptor sites on the postsynaptic cell membrane to stimulate the generation of another impulse.
Excitatory neurotransmitter
A synapse, chemical signals called neurotransmitters cross these gaps, carrying on the signal.