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NEURAL TRANSMISSION

NEURAL TRANSMISSION. Neurons Electrical and Chemical Transmission. Neurons . Neurons. Glial Cells. Astrocytes Contact blood vessels and neurons transport chemicals from blood to neurons Oligodendrocytes Myelinate CNS axons Schwann cells Myelinate PNS axons

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NEURAL TRANSMISSION

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  1. NEURAL TRANSMISSION Neurons Electrical and Chemical Transmission

  2. Neurons

  3. Neurons

  4. Glial Cells • Astrocytes • Contact blood vessels and neurons • transport chemicals from blood to neurons • Oligodendrocytes • Myelinate CNS axons • Schwann cells • Myelinate PNS axons • Guide regeneration after damage • Radial glia • Guide neural migration during development

  5. CELL MEMBRANES • Membrane Structure • Semipermeable lipid bilayer • Proteins • Ion channels • Transport pumps • Receptors

  6. MEMBRANE POTENTIAL

  7. MEMBRANE POTENTIAL • Electrochemical Gradient • Electrostatic Forces • Electrical gradient • Opposite charges attract, • Same charges repel • Diffusion Forces • Concentration gradient

  8. RESTING MEMBRANE POTENTIAL • Diffusion Forces • Na+ and Cl- in • K+ out • Electrostatic Forces • Na+ and K+ in • Cl- out +

  9. MEMBRANE POTENTIAL • Na+/K+ Pump • Compensatory Mechanism • Active when intracellular Na+ high • Neutral or inactive when intracellular Na+ low

  10. ACTION POTENTIAL

  11. ACTION POTENTIAL

  12. CONDUCTION OF A.P.

  13. SYNAPTIC TRANSMISSION NEUROCHEMICAL SYNAPSES

  14. SYNAPTIC COMMUNICATION • POSTSYNAPTIC POTENTIALS • Excitatory PSP • Inhibitory PSP • Electrical Synapses • Gap junctions • Neurochemical Synapses

  15. Structures of Neurochemical Synapses • Presynaptic Membrane • Postsynaptic Membrane • Synaptic Vesicles • Synaptic Cleft • Receptor Sites

  16. Steps In Neurochemical Transmission • Synthesis • Storage • Neurotransmitter Release • Receptor Activation • Neurotransmitter Deactivation • Enzymatic Deactivation (Metabolism) • Reuptake

  17. Steps in Neurochemical Transmission

  18. SYNTHESIS

  19. Receptor Activation • Ionotropic Receptors • ligand gated ion channels • Metabotropic Receptors • G proteins • Second Messengers

  20. Neurotransmitter Inactivation • Enzymatic Degradation (Metabolism) • Acetylcholine is inactivated by an enzyme, Acetylcholinesterase (AChE). • The monoamines are inactivated by the enzyme, Monoamine Oxidase (MAO) • Catecholamines (DA, NE, E) are also inactivated by and Catechol-O-Methyltransferase (COMT). • Reuptake • The monoamines are also inactivated through reuptake.

  21. MAJOR NEUROTRANSMITTERS • Acetylcholine • Monoamines • Catecholamines • Epinephrine • Norepinephrine • Dopamine • Indoleamines • Serotonin • Amino Acid Transmitters • Glutamate, Aspartate • GABA, Glycine • Neuropeptides • Enkephalins • Endorphins

  22. Cholinergic Pathways

  23. Dopaminergic Pathways

  24. Noradrenergic Pathways

  25. Serotonergic Pathways

  26. Neurochemical Pathways • Dopamine • Nigrostriatal Pathways (Substantia Nigra  Basal Ganglia) • Mesolimbic, Mesocortical Patways (VTA  NAc and pfCTX) • Most widely studied neurobiology theory of drug dependence relates to dopamine

  27. Neurochemical Pathways • Acetylcholine • Pontine nuclei • involved in components of REM sleep • Basal Forebrain • Reduced quantities found in Alzheimer’s patients • Norepinephrine • Locus Coeruleus  Forebrain • Stimulant drugs may induce wakefulness through these pathways

  28. Neurochemical Pathways • Serotonin (5-HT) • Raphe Nuclei • Research on weight control, aggressiveness, and depression are centered on 5-HT • GABA • Widespread in CNS • Related to seizures • Endorphins • Spinal cord and midbrain • Involved in body’s natural mechanisms for pain relief

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