Exam2ReviewSheet - Exam 2 Review Sheet Neurons and Synaptic...

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Exam 2 Review Sheet Neurons and Synaptic transmission - Synapses are the site of action for most psychoactive drugs - Neurons (cells found in the nervous system) are made up of the following: o Soma: cell body o Axon: conducts signal down neuron (output) o Dendrites and spines: receive incoming signals from pre-synaptic neuron o Synaptic vesicles: holds neurotransmitters (inside cell) o Synaptic clefts: space between pre and post-synaptic neurons o Pre-synaptic neuron: sends signal to pre-synaptic neuron o Post-synaptic neuron: receives signal from pre-synaptic neuron o Glia: cells that provide support and protections for neurons - Cell-to-cell junctions: o Tight junctions: membranes are fused o Gap junctions: small cleft (2-4nm); electrical synapse o Chemical synapse: cleft is bigger (20-30nm); polarized (more negative inside) - Multiple types of connections : axondentritic (axon to dendrite), endrodentritic (dendrite to dendrite), axoaxonic (axon to axon), etc. Steps in Synaptic Transmission: - Synthesis of NT - Transport of NT - Storage into vesicles - Release of NT: o Release in detail ( excitation–secretion coupling ): Depolarization (voltage of neuron Voltage-gated calcium (Ca++) channels open Ca++ rushes into cell Bind to Ca ++ (calmodulin protein kinase) Phosphorylation of synapsin I Vesicle move to site of release Exocytosis (neurotransmitters are released into the synaptic cleft) Diffusion of neurotransmitters - Inactivation -Neurotransmitters are inactivated in the following ways: o Reuptake: neurotransmitters go back into via transporters o Enzymatic degradation: metabolism, excretion, cycling Neurotransmitters: Classical vs. Neuropeptides - Classical: small water soluble molecules with amine; formed from dietary precursors. o Phenylethylamines: dopamine (DA), norepinephrine (NE), epinephrine (E). tyramine, etc. o Indolamines: serotonin (5-HT), tryptamine, melatonin, etc. o Cholinergics: acetylcholine, etc. o Amino acids: glutamate, gaba, etc. - Neuropeptides: produced via protein synthesis; includes enkephalins, substance P, neurotensin Receptors - Classification by location: o Postsynaptic o Autoreceptor: refers to transmitter receptors, on or near pre-synaptic terminals, which are sensitive to the transmitter(s) released by the terminal itself (inhibitory) Presynaptic, Somatodendritic, Terminal release-modulating, synthesis- modulating, impulse-modulating (detects how much NT to inhibit or to make more) - Classification by transduction mechanism:
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o Ligand-gated channels: (ligand = drug, NT, hormone, anything coming to bind) Binding site is coupled to the ion channel The transmitter or drug gates the channel Ionotropic receptors (the ligand binding site is an integral part of the receptor molecule Ligand opens channel ions Fow down concentration gradient Rapidly reversible • Examples: o Nicotinic acetylcholine receptor
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Exam2ReviewSheet - Exam 2 Review Sheet Neurons and Synaptic...

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