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Excitatory postsynaptic potential - Wikipedia, the free encyclopedia a.new,#quickbar a.new{color:#ba0000} /* cache key: enwiki:resourceloader:filter:minify-css:5:f2a9127573a22335c2a9102b208c73e7 */ Excitatory postsynaptic potential From Wikipedia, the free encyclopedia   (Redirected from Excitatory) Jump to: , This single EPSP does not sufficiently depolarize the membrane to generate an action potential. The summation of these three EPSPs generates an action potential. In neuroscience, an excitatory postsynaptic potential (EPSP) is a temporary depolarization of postsynaptic membrane potential caused by the flow of positively charged ions into the postsynaptic cell as a result of opening of ligand-sensitive channels. They are the opposite of inhibitory postsynaptic potentials (IPSPs), which usually result from the flow of negative ions into the cell or positive ions out of the cell. A postsynaptic potential is defined as excitatory if it makes it easier for the neuron to fire an action potential. EPSPs can also result from a decrease in outgoing positive charges, while IPSPs are sometimes caused by an increase in positive charge outflow. The flow of ions that causes an EPSP is an excitatory postsynaptic current (EPSC). EPSPs, like IPSPs, are graded (i.e. they have an additive effect). When multiple EPSPs occur on a single patch of postsynaptic membrane, their combined effect is the sum of the individual EPSPs. Larger EPSPs result in greater membrane depolarization and thus increase the likelihood that the postsynaptic cell reaches the threshold for firing an action potential.

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Overview

EPSPs 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 excitatory synapses, the ion channel typically allows sodium into the cell, generating an excitatory postsynaptic current. This depolarizing current causes an increase in membrane potential, the EPSP.

Excitatory molecules

The neurotransmitter most often associated with EPSPs is the amino acid glutamate, and is the main excitatory neurotransmitter in the central nervous system of vertebrates. Its ubiquity at excitatory sy... mehr

Excitatory aus Wikipedia. Zum Beitrag