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This 6 page Class Notes was uploaded by Tayler Osborn on Wednesday February 11, 2015. The Class Notes belongs to PSY:2701:0AAA at University of Iowa taught by Mark Blumberg in Spring2015. Since its upload, it has received 113 views. For similar materials see Biological Psychology in Psychlogy at University of Iowa.
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Date Created: 02/11/15
Neurophysiology Neurophysiology D the life processes within neurons using chemical and electrical signals Began by Otto Loewi 0 Used two frog hearts kept alive in different uid dishes Stimulated Vagus nerve Heart rate slowed Extracted uid from dish injected into dish B B s Heart Rate slowed o Showed presence of chemicals and ability for chemical reactions to stimuli Electrical Transmission and Potentials 3 States in Nervous System 0 Resting Potential Neuron is inactive 0 Action Potential Propagation of signals down axon o Postsynaptic Potentials Initiated at postsynaptic sites dendsoma Graded local passively transported decaying Resting Potential Passive Processes o Diffusion o Selective Permeability o Electrostatic Forces Opposites attract Active Processes 0 Ion Pumps K moves freely through pumps controlled by equilibrium 0 At resting potential electrical forces are equal Action Potential o Operates by Rate Law 0 Allor None Law AP s re completely or not at all No in between 0 Unmyelenated AP s o Slower conduction 10 ms 0 High energy use 0 Myelenated AP s 0 Fast conduction 150 ms 0 Low Energy Use 0 Spatial Summation o Summation of potentials originating from different parts of cell body AP only when summation reaches 40mV Temporal Summation o Summation of potentials reaching hillock at different times If they occur close enough may result in AP Stages of an Action Potential 0 At Resting Potential RP o 60mV 0 Open K Channels K Leaves because of o Diffusion 0 Lower concentration Allows for Equilibrium of K outge of cells during rest K pulled back in because of 0 Electrical force of innercell negat vity o NaV Channels closed Na being repelled Na drawn to cell because of Diffusion o MUCH higher concentration of Na outside of cell Even during Action Potential there will always be more Na outside of the cell 0 Electrical force 0 Protein negativity draws positive force 0 At Action Potential AP 0 40mV 0 Absolute Refractory Period D peak to valley NaV Channels open In ux of Na depolarizes cell 0 Relative Refractory Period NaV Channels are inactive Different from Closed 0 Ball amp Chain covers opening K Channels open KV and K Leak Channels 0 Re or Hyperpolarizes Cell 0 Repolarization NaV Channels are closed K Leak Channels open to return to 60mV Steps in Chemical Transmission Action Potential propagated down axon 0 One action potential depolarizes that part of membrane That depolarizes the next And the next And the next 0 side note myelin forces channels closed to force AP down faster 0 Gaps between myelin called Nodes of Ranvier Presynaptic membrane depolarized o In ux of Ca2 Ca2 forces vesicles to fuse with membrane Neurotransmitters released into synaptic cleft Transmitters bind to receptors on postsynaptic membrane 0 lonotropic Receptors the quick ones Ligand Gated Channel 0 Most Neurotransmitter Channels Inhibitory and excitatory postsynaptic potentials are activated Postsynaptic Terminal receives graded potentials 2 Types of Postsynaptic Graded Potentials o Excitatory Postsynaptic Potential Tells neuron to excite o Inhibitory Postsynaptic Potential Tells neuron to hold back Leftover enzymes in Synaptic Cleft must be taken care of o Enzymes present eat excess neurotransmitters o Reuptake occurs Leftover Neurotransmitters are reabsorbed into presynaptic membrane 0 3 Ways 0 Binds to Presynaptic Autoreceptor o Reuptake Absorbed back into presynaptic terminal 0 Enzymes break down excess neurotransmitters Criteria for Neurotransmitter Function Exists in presynaptic terminals Presynaptic Cell can synthesize substance 0 Released in signi cant quantities because of action potential 0 Appropriate receptors exist on postsynaptic membrane 0 Experimental application causes same reactionchanges in synapse Blocking release of the substance preventsaffects postsynaptic cell Major Neurotransmitters Acetylcholine Ach 0 Motor function 0 Learning and memory Only neurotransmitter used in neuromuscularjunctions Blockage of ACh D no movement 0 Receptors Nicotonic lonotropic receptor 0 Quick receptor that acts as a channel allowing for quick movement of material one at a time Muscle Muscarinic o Metabotropic Slow receptor because ligand must bind to receptor which then releases subparticle to open channel Slow to openshut moves more than one particle at a time Organsbrain GABA 0 Major inhibitory neurotransmitter Glutamate 0 Major excitatory neurotransmitter Dopamine DA 0 Reward 0 Motor Origin Substantia Nigra Pathways Mesostriatal 0 Motor pathway Mesolimbocortical o Reward pathway Seratonin 5HT 0 Sleep 0 General arousal Origin Raphe Nuclei Norepinephrine NE 0 Origin Locus Coeruleus Adrenaline o Drives Fight or Flight response Hypothalamus stimulates release from Anterior Pituitary Channeopathies Certain disorders are related to malfunctions in certain channels Toxins o 39ITX Puffer sh Blockschannels o BTX Rainforest frogs Leaves channels open Binding A 39nity o A chemicals likelihood to bind with a receptor 0 If A and B are present in equal amounts but B has a higher af nity than A then B is more likely to bind to a receptor DoseResponse Curve o Potency o The chemicals power to affect the mind or body If it takes less of A to get to a point than of B then A is more potent 0 Ef cacy o Somethings ability to produce a desired result 0 Therapeutic Index 0 Space between Effective dose dosage required to get a result and Lethal Dose close it takes to kill someone 0 Functional Tolerance o The change in postsynaptic synapses in response to abnormal exposure DownRegulation 0 Loss of receptors in response to drug UpRegulation o Gaining receptors in response to drug
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