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Announcements Pick up & keep Quiz 1 from piano Pick up copy of Androstenedione paper for Lab next week Monday Quiz on Endocrine Chapter and Case Studies Lab Check email & website over weekend for updates Ch 6 Nervous System Part A and B • • • • • • • • Ch 6 Part A: Basic terms Cell types of Nervous Tissue Components of a neuron Components of a reflex arc Axonal regeneration Ohm’s Law Origin of resting membrane potential Equilibrium Potentials (Nernst potentials) Important Terms (we’ll know these and many more as we move through Chapter 6 Cell Body (soma) Afferent Neuron Astrocyte = Astroglia Axon Terminal Myelin Dendrite Microglia Node of Ranvier Neurotransmitter Interneuron Schwann cell Axon with axon hillock Oligodendrocyte Synapse Ependymal cell Axonal pathfinding Efferent Neuron Nervous tissue = Neurons (for electrical signalling) and Glial cells (for…..) Know relative numbers (neurons:glia) and various functions of CNS Glial cell types. Membrane Potential & Structure make Neurons good Electrical Communicators ligand-gated ion channels in membranes of dendrites and soma…. Graded potentials } receiving Axon hillock “integrates.” Decremental conduction in dendrites and somatic membranes Unidirectional Non-decremental conduction in axons } sending voltage-gated ion channels in membrane of axon hillock and axon….. Action potentials Nodes of Ranvier ~1mm apart In PNS Not all axons are Fig. 06.02 myelinated, although all axons are enveloped by Schwann cells in CNS or Oligodendrocytes in PNS What are the advantages of myelination? In CNS Lightly myelinated axon Communication in The Vertebrate NS Reflexes require some part of the CNS (i.e. frog lab) Peripheral nerves are “mixed” (have sensory & motor axons) Blood pressure Blood gases and pH Muscle stretch Skin temperature Hair movement Light Taste Odor Touch Pain Etc. Signalling over short and long distances Dimensions of neurons Descending neurons (interneurons) from brain to spinal cord Sensory (afferent) neurons from hoof to brain Nodes of Ranvier are 1 mm apart. How many Schwann cells to myelinate the 2 meters of a sensory axon from hoof to dorsal root ganglion near spinal cord? Fig. 06.03 Axonal Transport • Orthograde = Anterograde = from soma to terminals – slow……1-2 mm/day – fast …..200-400 mm/day (kinesin) • Retrograde = from terminals to soma – fast….200-400 mm/day (dynein) • What gets transported and why? • Axonal transport is too slow for rapid signalling, so… Who Cares? Alayna Davis October 1992 Age 5 October 31, 1992 October 1998 Regeneration in CNS?