<unk> s in living cells are caused chemically. When an active presynaptic cell releases neurotransmitters into the synapse, some of them bind to receptors on the postsynaptic cell. Many of these receptors contain an ion channel capable of passing positively-charged ions either into or out of the cell (such receptors are called ionotropic receptors). At<unk>  synapses, the ion channel typically allows sodium into the cell, generating an<unk>  postsynaptic current. This depolarizing current causes an increase in membrane<unk> , the<unk> .
Excitatory postsynaptic potential
Inhibitory postsynaptic potential
Excitatory synapse
Resting potential
Ventricular action potential
Chemical synapse
Membrane potential
Sodium channel