Chapter 45 ELECTRICAL SIGNALS IN ANIMALS

Chapter 45 ELECTRICAL SIGNALS IN ANIMALS -...

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Chapter 45  ELECTRICAL SIGNALS IN ANIMALS Chapter 45  ELECTRICAL SIGNALS IN ANIMALS Communication – The Nervous System Nervous System *General Scheme, fig 45.1 *Stimulus excites a receptor (sensor) – Name some stimuli. *Receptor sends info via sensory neuron (nerve cell) to an… *Integration center (CNS) that processes info (interneurons ) and sends instructions via a… *Motor neuron to an effector (skeletal muscle, etc.) *The sensory or input pathway is also called the afferent pathway. *The motor or output pathway is also called the efferent pathway. *Soma or cell body *Dendrites *Axon *Axon hillock – spot where axon extends from soma. *Neuroglia = helper cells that nourish and protect neurons. Examples: *Microglia – *Astrocytes – ***Schwann cells (PNS) and oligodendrocytes (CNS) form myelin sheaths = insulation. How Do Cells Generate Electrical Signals? *Review: *Atoms that lose electrons become positive ions *Atoms that gain electrons become negative ions. *Ions of opposite charges are attracted to each other. To separate them requires energy. Charge separation represents potential energy – like your car battery. *Membrane potentials (electrical) *In cells, different concentrations of ions on each side of a membrane produces an electrical potential or voltage. *Ions must move through channels – 3 types: *Ligand gated – a molecule binds to the channel protein and opens/closes the gate. *Voltage gated – the channel opens/closes at a certain membrane voltage. *“Leak channels ” – always open. *Resting Membrane Potential, fig 45.4 *Inside the cell are proteins with negative charges and a high concentration of K + but a low concentration of Na + . *Outside the cell there is a high concentration of Na
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This note was uploaded on 09/08/2011 for the course BIOL 1403 taught by Professor Dini during the Fall '09 term at Texas Tech.

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Chapter 45 ELECTRICAL SIGNALS IN ANIMALS -...

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