35. Electrical signaling Part 1

35. Electrical signaling Part 1 - excite.org(anism):...

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1 excite.org(anism): Electrical Signaling Today’s lecture – we’ll use clickers Friday’s lecture – both sections in BPS 1250 at 9 AM! Universality of sensory-response systems Madigan et al. Fig. 8.24 Rick Stewart (CBMG) Three step process: sensation-integration-response Bacterial chemotaxis Human nervous system F Fig. 45.1 Universality of sensory-response systems F. Fig. 47.3 Three general classes of communication signals Chemicals via diffusion - rapid communication over short distances within cells or between cells (e.g., neurotransmitters) Electricity via ion flows - very rapid communication over longer distances along individual cells or between cells (e.g., action potentials) Chemicals via bulk flow - slower communication over longer distances in body fluids of large organisms (e.g., endocrine hormones) The hierarchy of electrical signaling in animals Molecular level - transmembrane ion flows Cellular level - lateral electrical signaling Tissue level - cell-to-cell signaling Organ level - signal processing System level - perception, integration, and response Higher-order phenomena - consciousness, learning, memory, etc.
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2 Lecture outline Neuron - fundamental cell of nervous systems Membrane proteins - molecular players in electrical signaling Axons - action potentials Synapse - narrow gap between adjacent neurons Neurotransmitters - chemical communication across the synapse Dendrites - graded potentials Evolution of electrical signaling Challenges: How to evolve a communication system for coordinating feeding behavior in often mobile multicellular organism How to evolve this system by using available proteins, cell structures and their functions Solution: Evolve a specialized cell (= neuron) with an extended axon (up to > 1 m in some vertebrates) for very rapid, long distance communication Axon is specialized for conducting the action potential - are electrical signals propagated along the cell membrane are based on fundamental physical and chemical processes Utilize voltage-gated channels that have ancient evolutionary origin
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This note was uploaded on 02/01/2012 for the course BSCI 207 taught by Professor Higgins during the Spring '08 term at Maryland.

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35. Electrical signaling Part 1 - excite.org(anism):...

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