How can neurotransmitters both inhibit and excite

[CrazCo]

That doesn't make sense at all, they're opposite :S

[Genecks]

To excite an action potential and to inhibit an action potential.

I think....

 

http://en.wikipedia.org/wiki/Inhibitory_postsynaptic_potential

http://en.wikipedia.org/wiki/Excitatory_postsynaptic_potential

 

http://en.wikipedia.org/wiki/Inhibitory_postsynaptic_potential#Inhibitory_Molecules

http://en.wikipedia.org/wiki/Excitatory_postsynaptic_potential#Excitatory_molecules

[CrazCo]

je t'aime

[CharonY]

To put it simply, it depends on what signaling pathways the neurotransmitters activate on the postsynaptic cell. This again depends on the type of the receptors to which the transmitters bind. The neurotransmitter themselves have no direct activating or inhibitory activities other than causing conformational changes in the receptor leading to whatever activating or inhibiting signaling cascade the receptor may cause.

[CrazCo]

thank you, i now understand

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is there such thing as chlorine channels in the neural membrane? and is the concentration greater on the inside or outside of it when we're talking about chlorine ions. i am thinking if one binded to a chlorine receptor depending on which side is more concentrated it would diffuse and cause it to either be excited or depressed? is this true

[CharonY]

The chloride (not chlorine!) ions are higher on the outside than in the inside (the fraction that is relevant for the membrane potential that is). GABAergic receptors are a common class. If chloride channels open it counters the depolarization of the membrane (by allowing chloride influx). That is why GABA is usually a inhibitory neurotransmitter.