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PSY396 May 15.docx

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PSY396 March 15, 2013 st Email topic by may 31 - How receptors decode the message and finally what happens level of whole cell Basic principals - Cell body and long axon to axon terminal to post synaptic neurons - Gfp staining and - Axonal branches from main body of axon and dendtritic processes - Flow from dendrite and whether to fire or not - When message along axon reaches terminals Next - Now trans releases Chemical synaptrical trans - Basic elements of the synapse - Nt – chemicals used as signals from one neuron to another carrying message - Cleft – space between the neurons, not contact but space terminal button and dendritic branch of ps neuron - Vissicals – membrane enclosed strorage containers for chemicals and nts - Highly polarized – transmitted form pre to post not absolute bc some synapse post send message back to modulate message from pre syn not enough or more - Little about reverse direction Digression - Synapse not only way neurons communicate - Most common and interesting - Gap junctions - Phsycual connection between cytoplasm of one and another neuron Gap junction - Two layers of membrane of one neuron and another - Physciall bind two membranes together and create channel beidge that connects cytoplasms of two neurons - See the zipper of two neurons and from above view - Protein – conexins Next - Features - Transmission is rapid and bidirectional - Nature of connection is connexons proteins - Message is usually just an ion current - Positive one ten diffuse to neighboring cell through gap junction - Ion current not only nature of the current – larger and smaller moiecules as well - Message coded by amount though channels - Cytoplasm of one neuron shared with other - Abother way neurons comm. Is volume transmission – - One neuron and axon terminal connect with dendrite of another synaptic transmission occurs at terminal end - It is slow - In addition snaptic transmission - Diffuse at the synapse causing effects elsewere - Volume transmission – ach/ gap junction not need to know a lot about just what is posted - Chemical synapse most common and relavent conenciton between neurons Back to syn trans - Strcurtural features - Cleft empty space and post synaptic neuron recieveing end the dendritic branch - Recieveing end can occur at soma or even axon - Nts stored in vesicles in terminal buton, vesicles fuse with membrane and diffuse across cleft and bind to post receptors producing some response in post neuron - Nt itself is a message – calcium is more of an outcome - Process - How fuse Next - Define neurotransmission in 10 steps can be substeps fused together - Good question for exam – tell the whole story makes sense - Vesicels present in terminal button of axon filled with nts - Ap arrives to terminal change in polarization of membrane in terminal button causes opening of voltage gated calcium channels - Allow influx of ca ion in terminal button - Once calcium entered calcium depednednt mechanism drives vesicle to dock on membrane of terminal buttion then open up and spill contentns - Nt bind to receptors in post - Producing a physiological response – in response receptor open up act as ion channel and allow nt to diffuse in post - Inactivation of nt released - Ap to release of nt - Ca in vesicle fuse with membrane and spill nt in cleft and bind to receptors - Nt cleared up or inactivated Whats needed - Cells need to provide infrasteucuture to support all steps - Need to pack nt in vesicles - 2 nd - Bind vesicle to membrane and cause opening of vesicle - 3 rd - Response - 4 th - Clean up 1 - 2 ways done st - 1 - Done for most classical nts - In soma in cell body all machinery needed to synth these nts made and sent to terminal button - And precursors molecules for synthesise provided in soma sent to terminal button - Precursosrs in terminal button through reuptake - Main feature all main parts made in soma - In terminal button enzyme make nts use precursors and another set of transporters (membrane tranporters) on membrane plug nts into vesicles - Can be small or large - Vesicles created by membrane - Used vesicle bud away from membrane - Liquid bilayer make up vesicle - All pieces made in cell body to terminal button and nts synth and packed at button 2 nd - 2 - Nts made in the soma packed vesicles in en reticulum and golgi apparatus - Machinery in soma nts button - Neurpeptides mechanism 2 - Classical nts simple small lmoleculse - Nueropeptides are polypeptides – string of aa smaller then proteins - 2 - Gogli and er similar in structure to cell membrane – Relasease of nts - Once ap arrive terminal button - Driven mainly by calcium ions - Ap arrive terminal button open voltage gated ca channel and ca driven in cell - And binds to calm - Calium calm complex activate kinase which is enzyme adds phosphate group on other proteins (kinase activator of other proteins) - Two Syanpisn will bind with protein kinase Electron microscopy 4th - Just diffusion random movement – some absorbed or inactivated - Enzyme degradation –just float in cleft - Glial cells – form myelin sheath – some immune functions and some supportive strcuuture role - Reuptake – transporter proteins in membrane once nt released and nts taken back up - 4 just combination similar to reutake taken by pre not nts but precursors – enzymes break then nt down Drugs can interfere - All processes depend on different proteins and can be effected by a drug Summary - Nts synth in cell in body or terminal button stored in vesicles reelased in cleft and activation Nts vs neuropeptides Nts - Classical nts - Chemicals that serve as messengers between neurons - Table 3-1 full list of the nts maybe 10 of them we will talk about - Nts ex or in based on response produced in post - Nt not only determinant whether post be ex or in - Each neuron produces only one nts true for classical nts but neurons release many neuropeptides either on own or together with classical nts Classes of nts - Different classes based on chemical characteris of nts molecule - Mono – 2 sub groups - And aa – widespread – glut ex and gaba primary in - And peptides Definition - 5 conditons must fill - Nt into classical and neuropeptides and classical are nt and neuropeptides are neuroppeptides - 1 – must exist in presnaptic terminal, enzyme for synthesizing in terminal or body - 2 – released ap arriving - 3 – receptors that respond to nts - 4 – blocking of nts stop message going across Neurpepetide - Known about them long time classical nts - Peptides - Made string of aa – made by transcribing dna to rna then rna is translated to string of aa - And string of aa Is precursor to peptide itself - Filled in soma - Co transmitter – cell releasing classical nt primary signaling chemical release some co nt and these cotransmitters modulate post neuron response - Slow - Dense core – part vesicles set in membrane is active zone for classical classical nts – np package vesicles anywhere in terminal button so need stronger stimulation not primed for released need stronger sustained stimulation to reach cell membrane Biosynt - Dna to rna and string to aa - Then string of aa polypeptide precursos - Undergo several steps of modification of slicing of original string of aa - These modification first in er and then in golgi app and then while traveling in vesicle to leave - Wait in terminal Regulation - Main manner regulated is first step – being decided what genes to express - And polypeptide precursors to be made - Not released at active zones - Where vesicles sit primed to bind to membrane - Theses vesicles sit away from active zones need more time and activiaiton to reach membrane - Similar to classical they are degraded in different ways some enzymes in cleft or diffuse away from cell - Nps not have own tran
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