Medsci 206 - Module A (Synapses and plasticity, CNS cells, development) Questions And Answers A+ Graded 2024/2025

Medsci 206 - Module A (Synapses and plasticity, CNS cells, development) Questions And Answers A+ Graded 2024/2025 neuron structure - ANS-polarised cells axon - presynaptic - site of outgoing info, contact other neurons dendrites - postsynaptic - side of synapses (incoming info) synapses - ANS-specialised site of neuron-neuron contact rapid communication form neuronal circuits transform electrical info to chemical then back to electrical information processing units of the brain parts of synapses - presynaptic terminal (axon bouton) - ANS-active zone synaptic vesicles neurotransmitter release convert electrical info (AP) into chemical info (NT) parts of synapses - postsynaptic apparatus (on dendrites) - ANS-postsynaptic density (varied in nature) postsynaptic receptors reception of NT and convert chemical info (NT) into electrical info (ion flow) presynaptic transmitter release - ANS-transmitter synthesised and stored in vesicles -> AP invades presynaptic terminal -> depolarisation cause opening of voltage-gated Ca2+ channels -> influx of Ca2+ through channels -> Ca2+ cause vesicles to fuse with membrane -> transmitter released into synaptic cleft via exocytosis -> transmitter binds receptor molecules in postsynaptic membrane -> opening or closing of postsynaptic channels -> postsynaptic current cause excitatory or inhibitory postsynaptic potential which changes excitability of postsynaptic cell SNAREs - ANS-transmitter release vesicle docks -> SNARE complexes form to pull membranes together -> entering Ca2+ binds to synaptotagmin which then catalyses membrane fusion postsynaptic transmitter receptors - ligand gated ion channels - ANS-rapid NT binds -> channel opens -> ions flow across membrane postsynaptic transmitter receptors - G protein couples receptors - ANS-modulatory NT binds receptor -> G protein (bound to internal side of receptor) activated -> G-protein subunits or intracellular messengers modulate ion channels -> ion channel opens -> ions flow across membrane EPSP - ANS-excitatory postsynaptic potential depolarises cell -> increase likelihood of AP in postsynaptic neuron IPSP - ANS-inhibitory postsynaptic potential hyperpolarises cell -> harder to reach threshold -> decrease likelihood of AP in postsynaptic neuron Inhibitory synaptic transmission - ANS-mediated by interneurons (inhibitory neurons) which release inhibitory NT (eg GABA and glycine) GABA and glycine receptors on postsynapse are permeable to chloride ions -> Cl- influx makes RMP further from threshold, inducing hyperpolarisation (make RMP more negative) excitatory synapses - ANS-... Continues...