Exam 2 Notes
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This 4 page Study Guide was uploaded by Huda Khan on Monday September 14, 2015. The Study Guide belongs to PSYC 465 at Towson University taught by Dr. Devan in Fall 2016. Since its upload, it has received 26 views. For similar materials see Physiological Psychology in Psychlogy at Towson University.
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Date Created: 09/14/15
Membrane Potential The difference in electrical charge between the inside and outside of a cell Polarization The neuron is said to be polarized a 70 mV charge is built up across the membrane Hodgkin and Huxley Concluded that there are active mechanisms in the cell membrane to counteract the passive in ux in ow of Na ions and the passive ef ux out ow of K ions Function of Sodium Potassium Pump exchanges 3 sodium ions out of the neuron for every 2 potassium ions brought into the neuron This is an active mechanism that requires energy ATP to maintain the resting membrane potential Postsynaptic potentials Depolarization decreases the resting membrane potential eg from 70 to 67 mV Hmergolarization increases the resting membrane potential eg from 70 to 72 mV Depolarizations are called Excitatory postsynaptic potentials EPSPs they increase the likelihood that the postsynaptic receiving neuron will itself generate an action potential Hyperpolarizations are called Inhibitory postsynaptic potentials lPSPs they decreases the likelihood that the postsynaptic neuron will generate an action potential Characteristics of Action Potentials Allor none like ring a gun Propagated once they begin they travel all the way down the axon Nondecremental the height is the same from beginning to end Conduction Speed of Axons depends on Diameter of axon faster in large axons Myelination faster in myelinated axons Passive movement of AP within myelinated portions occurs instantly Nodes of Ranvier unmyelinated Where ion channels are foundWhere full AP is seenAP appears to jump from node to nodeSaltatory conduction Saltatory conduction Transmission of APs in myelinated axons saltare to skip or quotjumpquot AP conduction along myelinated segments of an axon is passive ie it travels fast but gets weaker the farther it goes The signal is still strong enough to generate a full AP at the next node Dendritic Functions Some can generate APs that travel in either direction Dendritic spines restrict chemical changes to the immediate area of the synapse they compartmentalize the dendrite Spines change rapidly within minutes to hours in shape and number in response to neural stimulation Thresholds and Refractory Period Absolute refractory a brief period 12 ms after the initiation of an AP during which it is not possible to elicit another AP Relative refractory the period in which it is possible to re an AP but only if higherthannormal levels of stimulation are applied Synaptic transmission Two types of synapses functions Directed the site of neurotransmitter release and receptor activation is in close proximity Nondirected the site of release is at some distance from the site of reception 2 general types of neurotransmitters Small moleculeSynthesized in the terminal button and packaged in synaptic vesicles Large molecule peptideAssembed in the cell body on ribosomes packaged in vesicles and then transported to the axon terminal Different categories of small molecule neurotransmitters Amino acids the building blocks of proteins Usually found at fast acting directed synapses in the CNS Glutamate Most prevalent excitatory neurotransmitter in the CNS GABA synthesized from glutamate Most prevalent inhibitory neurotransmitter in the CNS Aspartate and glycine Monoamines all synthesized from a single amino acid Effects tend to be diffuse Catechoamines synthesized from tyrosine Dopamine Norepinephrine Epinephrine Indolamines synthesized from tryptophan Serotonin 5HT Soluble gases exist only brie y Nitric oxide and carbon monoxide Retrograde transmission backwards communication Acetylcholine ACh activity terminated by enzymatic degradation Acetyl group choline neuromuscularjunction Major excitatory and inhibitory neurotransmitters Excitatory Glutamate Inhibitory GABA Neurotransmitter storage and release 2 main receptor types and activation Released neurotransmitter produces signals in postsynaptic neurons by binding to receptors Receptors are speci c for a given neurotransmitter Ligand a molecule that binds to another A neurotransmitter is a ligand of its receptor lonotropic receptor associated with ligandactivated ion channels Metabotropic receptors associated with signal proteins and G proteins Postsynaptic Presynaptic auto receptors 2 forms of receptor deactivation Reuptake neurotransmitter is taken back into the presynaptic terminal Enzymatic degradation neurotransmitter is broken down by enzymes 7 steps in synaptic transmission a Seven Prccesses in Neurotransmitter Acticn Neurotransmitter melesules are syn 7 Sti39nthleaizing theelees tram precurscrs enzymes under the influence at enzymes llNELIf thl Sl HEf Neuretransmitter meleetiles are Prg wwr g stated in vesicles v VESIIICIE Necrctransmitter malestiles that teait treat their vesicles V are rtestrcryert lay enzymes Degrad39w Acticri instantiate cause vesictes tc 39 fuse with the presynptlc membrane and release their necrctransmitter metesates inte the synapse Released neurctransmitter mciecutes bind with autcre cepters and inhibit subsequent neurotransmitter release Flaleased neurctransmitter mciecates bind to pastsynaptic receptcrs Flaleased neurctransmttrer mct V 7 39 la quot Ut re EPtEtr ecates are deactivated either by reuptake er enzymatic degradaticn steamytic recepticr Psychopharmacolog antagonist versus agonists drugs Agonists increase or facilitate activity Antagonist decrease or inhibit activity cholinergic antagonists muscarinic versus nicotinic mechanisms of action NMDA receptor coagonist and synaptic plasticity benzodiazepine effect at GABA receptors Mechanisms of drug action that affect steps in synaptic transmission Classes of neuroleptic drugs and speci city of dopamine receptor subtype drug action Extra credit multiple choice questions Characteristics of APs and PSPs Stages in neurotransmitter action synaptic transmission Mechanisms of drug action Changes to the dopamine theory and schizophrenia
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