Neuronal Communication: Electrical Potentials & Synaptic Transmission by Mary ET Boyle - P, Study notes of Philosophy of psychiatry

Download Neuronal Communication: Electrical Potentials & Synaptic Transmission by Mary ET Boyle - P and more Study notes Philosophy of psychiatry in PDF only on Docsity! 1 Neuronal Communication Mary ET Boyle, Ph.D. Communication within a Neuron • Measuring Electrical Potentials of Axons • The Membrane Potential • The Action Potential • Conduction of the Action Potential Mary ET Boyle COGS 1 2 The withdrawal reflex Mary ET Boyle COGS 1 neural circuits excitatory effects Inhibiting the withdrawal reflex Mary ET Boyle COGS 1 4 Copyright © Allyn & Bacon 2007 The brain inhibited the motor neuron to prevent the dish from dropping. Electrical Wire clectrade placed in seawater Records ot / changes in / membrane / potential displayed here Membrane potential (mV) 1 2 stimulus Time (msec) applied 6 Mary ET Boyle COGS 1 Mary ET Boyle COGS 1 7 Mary ET Boyle COGS 1 cation anion _ + Mary ET Boyle COGS 1 10 Mary ET Boyle COGS 1 The Action Potential-Animation http://bcs.whfreeman.com/thelifewire/content/chp44/4402s.swf Na+ Opens Na+ becomes Refractory K+ continues to leave cell. Causing the K+ Opens membrane potential to return to the resting potential. K+ channels lc ose. Na+ channels reset, ready for action again!Extra K+ outside diffuses away. 11 Mary ET Boyle COGS 1 21 Mary ET Boyle COGS 1 22 12 Mary ET Boyle COGS 1 23 Mary ET Boyle COGS 1 24 15 Mary ET Boyle COGS 1 Mary ET Boyle COGS 1 30 16 Mary ET Boyle COGS 1 31 Mary ET Boyle COGS 1 32 17 Mary ET Boyle COGS 1 33 Mary ET Boyle COGS 1 Nature Reviews Neuroscience 3, 641-653 (2002); doi:10.1038/nrn898 20 Metabotropic Receptors Mary ET Boyle COGS 1 Metabotropic receptors – 2nd messenger mediated Mary ET Boyle COGS 1 40 21 Mary ET Boyle COGS 1 Mary ET Boyle COGS 1 22 Mary ET Boyle COGS 1 Mary ET Boyle COGS 1 25 Mary ET Boyle COGS 1 Summation • excitatory or inhibitory Mary ET Boyle COGS 1 26 Neurotransmitter Deactivation • Degradation • Reuptake • Autoreceptors Mary ET Boyle COGS 1 Mary ET Boyle COGS 1 52 Copyright © Allyn & Bacon 2007 27 Mary ET Boyle COGS 1 53 Copyright © Allyn & Bacon 2007 Mary ET Boyle COGS 1 54 30 • ion channel – A specialized protein molecule that permits specific ions to enter or leave cells. • voltage-dependent ion channel – An ion channel that opens or closes according to the value of the membrane potential. • all-or-none law – The principle that once an action potential is triggered in an axon, it is propagated, without decrement, to the end of the fiber. Mary ET Boyle COGS 1 • rate law – The principle that variations in the intensity of a stimulus or other information being transmitted in an axon are represented by variations in the rate at which that axon fires. • cable properties – The passive conduction of electrical current, in a decremental fashion down the length of an , axon. • saltatory conduction – Conduction of action potentials by myelinated a ons The action potential appears to j mp from Mary ET Boyle COGS 1 x . u one node of Ranvier to the next. 31 • postsynaptic potential – Alterations in the membrane potential of a postsynaptic neuron, produced by liberation of neurotransmitter at the synapse. • binding site Th l ti t t i t hi h li d bi d– e oca on on a recep or pro e n o w c a gan n s. • ligand – A chemical that binds with the binding site of a receptor. • dendritic spine A small bud on the surface of a dendrite with which a terminal button Mary ET Boyle COGS 1 – of another neuron forms a synapse. • presynaptic membrane – The membrane of a terminal button that lies adjacent to the postsynaptic membrane and through which the neurotransmitter is released. postsynaptic membrane• – The cell membrane opposite the terminal button in a synapse; the membrane of the cell that receives the message. • synaptic cleft – The space between the presynaptic membrane and the postsynaptic membrane. Mary ET Boyle COGS 1 • synaptic vesicle – A small, hollow, beadlike structure found in terminal buttons, contains molecules of a transmitter. 32 • release zone – A region of the interior of the presynaptic membrane of a synapse to which synaptic vesicles attach and release their neurotransmitter into the synaptic cleft. • postsynaptic receptor – A receptor molecule in the postsynaptic membrane of a synapse that contains a binding site for a neurotransmitter. • neurotransmitter-dependent ion channel – An ion channel that opens when a molecule of a neurotransmitter binds with a postsynaptic receptor. Mary ET Boyle COGS 1 • ionotropic receptor – A receptor that contains a binding site for a neurotransmitter and an ion channel that opens when a molecule of the neurotransmitter attaches to the binding site. • metabotropic receptor – A receptor that contains a binding site for a neurotransmitter; activates an enzyme that begins a series of events that opens an ion channel elsewhere in the membrane of the cell when a molecule of the neurotransmitter attaches to the binding site. • G protein – A protein coupled to a metabotropic receptor; conveys messages to other molecules when a ligand binds with and activates the receptor. • second messenger Mary ET Boyle COGS 1 – A chemical produced when a G protein activates an enzyme; carries a signal that results in the opening of the ion channel or causes other events to occur in the cell.