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Lecture 17 ECEN5341/4341

Lecture 17 ECEN5341/4341. February 21, 2014. Nerve Cells. 1. Neurons, carry information 2. Glia Cells support functions of insolation and clean up of unwanted materials. A Neuron . Electrical Signal In the Body. 1. Nerves and Action Potentials 2. Activate Mussels

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Lecture 17 ECEN5341/4341

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  1. Lecture 17 ECEN5341/4341 February 21, 2014

  2. Nerve Cells • 1. Neurons, carry information • 2. Glia Cells support functions of insolation and clean up of unwanted materials

  3. A Neuron

  4. Electrical Signal In the Body • 1. Nerves and Action Potentials • 2. Activate Mussels • 3. Effect Growth Processes. • 4. Involved in Memory

  5. 1

  6. Cell Membrane Cartoon

  7. Cell Membranes • 1 Classical nerve cell • Na+outside =142mEq/L 1gr/dL=2.5mEq/L • Na+inside = 14 mEq/L • K+outside =4 mEq/L • K+inside = 140 mEq/L • Cl-outside = 103 mEq/L • Cl-inside = 4mEq/L • Enzymes also negative on the inside

  8. Diffusion Potential • 1. Basic equation 2. For J=0

  9. Active Pumps to Maintain Concentration Differences • 1. Na+ , K+ pumps • 2. Many other pumps for 80 substances? • Ca2+,Fe,I, Cl, Urate,sugars and amino acids • 3. All require energy. • 4. These all require protein channels. • 5. Co-transport of molecules say Na +Glucose into the cell.

  10. Na+ , K+ Concentration Gradients

  11. Relative Permeability of Membrane

  12. Action Potential • 1Trigered by • influx of Na+ as • summed by the • inputs from the • dendrites at • the cell body • 2. Terminated by • Outflow of K+

  13. Na+ Gate

  14. Channels

  15. Current Pulses

  16. Action Potential • 1 Propagates at constant • Amplitude for up to 3m • at speeds up to 100m/s • 2.Repeated and amplified • at the nodes of Ranvier

  17. Synaptic Junction Output Neurotransmitters

  18. A Different Approach to Cell Structure and the Function of Membranes. • 1. Reference • Cells, Gels and the Engines of Life by Gerald H. Pollack Published by Ebner and Sons Seattle Washington. 2001 • 2 On the Web Human Physiology - Cell structure and function for some good pictures and standard model with channels for Na , K

  19. Outline of Material • 1. Problems with the current model for cells • 2. Some properties water , H2O, Solutes , Ions and cell potential • 3. Properties of Gels and Cytoplasm , • 4. Phase Transitions a Mechanism for Action • 5. Action potentials.

  20. Some Problems. • 1. Not enough energy for all the pumps. • 2. Need 50 or more types of channels and pumps • 2. the concentration ratios and voltages are still there when the membrane is removed. • 3. You can still get an action potential to propagate along a nerve cell with no Na or K if you have enough Ca.

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