current is inward (negative current)■●EPSP - excitatory postsynaptic potential○Glutamate receptors where sodium enter more than potassium leaves○Excitatory synapse (glutamatergic) - release glutamate○At the axon hillock, swelling occurs - initial segment■First place with voltage gated sodium channels (determines if thecell has action potentials)
○No voltage gated sodium channels in dendrites○Cell gains +ve charge because of depolarization●IPSP - inhibitory postsynaptic potential○Chloride goes in○The inhibitory synapse isGABAergic- release of GABA○Here there is less likely to have action potentiaks in the axon hillock○Hyperpolarization●Technique of the week -patch clamp○Glass pipette electricallty conducted with heat○(1) cell-attached recording■Mild-suction and tight contact between pipette and membrane - noleakage of saline solution○(2) whole-cell recording■Strong pulse of suction and cytoplasm is continuous with pipetteinterior○(3) inside-out recording■Exposure to air and cytoplasmic domain is accessible○(4) outside-out recording■Pipette is retracted, ends of membrane anneal and extracellulardomain is accessible○Nobel prize in physiology or medicine 1991 -Erwin NeherandBertSakmann■Invented the patch clamp method■Discovered opening and closing of single ion channels●Spatial summation - spatial integration of EPSPs (interconnective)○2 EPSP signals in 2 different regions simultaneously - add them together○Here EPSP 2 is bigger than EPSP 1 as it does not dissipate much via potassium leak channels○This increases the chances of reaching threshold and causing action potentials○○Membrane length constant / potential■Dendrite - axial resistance / how thin■Exponential decay in space/ disapation■Vx = sum / Vtotal●We compare it to the threshold by doing -65 mV + Vx■Distance!■●Temporal summation - integration of EPSPs○Multiple EPSPs in the same region (no difference in distance here)○Glutamatergic○Each EPSP diminishes over time. Why?■●Summation of excitatory and inhibitory post-synaptic potentials○Spatiotemporal interaction of EPSPsandIPSPs - EPSPs in different regionsand IPSPs in same region but diff times○Chapter 4●Dermatomes (derma= skin,tones= slice)●There are four levels of the spinal cord (here is the order going head to toe):
○(1)Cervical- rostral, the head■Gray matter - cell bodies, dendrites●Larger ventral horn cuz lots of muscles in the arms■White matter - myelinated axons○(2)Thoracic- chest■Barely any gray matter○(3)Lumbar- legs■Dorsal horn(sensory) andventral horn (motor output and muscle contraction) now present●Bigger ventral horn than the other segments due to the large amount of muscles in the legs■Grey matter are cell bodies and dendrites primarily■White matter primarily myelinated axon (which myelin is fatty acid which reflects light)○(4)Sacral- caudal, back of legs and genitals●Each level has multiple segments (transverse sections/ across)●Each segment (vertibral, bone) each hasnerves(axons going from low to high that are inervated)going in●Primary afferents convey infor from skin to CNS - anterior lateral system○A beta axon - mechanosensory afferent fiber■Convey action potentials of touc■Methanal beta-afferents■To the dorsal root ganglion (DRG) - axon peripheral bran and central branch●Unusual morphology●Where axon cell bodies are from the skin■Axon enters bones to go to CNS (spinal cord)■Ascends to dorsal white matter of spinal cord
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Term
Fall
Professor
Gerlai
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