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Understanding Neuronal Membrane Potentials and Ion Movements

Explore the ionic basis for membrane potential, neuron structure, graded potentials, and action potentials. Learn about ion distributions, permeability, and specialized channels in neurons. Discover the role of Na+/K+ ATPase in maintaining ion balance.

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Understanding Neuronal Membrane Potentials and Ion Movements

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  1. State how movement of Na+, K+, Ca2+ or Cl- across a cell membrane will affect membrane potential. Explain the ionic basis for the resting membrane potential. Diagram a neuron and identify specialization. Describe the ionic basic for a graded potential,, EPSP, IPSP and action potential. Electrophysiology and neurotransmission

  2. Neuron basic structure and cell specializations

  3. Maintenance of ion distributions by Na+/K+ ATPase leaky K+ channels leaky Na+,Ca+,Cl- channels

  4. There are two primary determinants of the resting membrane potential. 1. Concentration of ions inside and outside the cell. 2. Permeability of the membrane to these ions. - Inside the neuron is high in K+ and low in Na+. - Outside the neuron it’s opposite, high in Na+, low in K+. - At rest, the permeability of the membrane is high for K+ and very low for Na+ and Cl-. For the moment we will assume that the permeability of the membrane to Na+ and Cl- is zero. Membrane potential would be = E K+

  5. 0.01 0.01 0.01 5 145) Vm 60 0.01 150 15) K+ is the most permeable to a cell membrane,but the Na+, Ca++, Mg++ and Cl- permeability is actually not zero. Use Goldman-Hodkin-Katz equation to calculate membrane potential based on permeabilities of multiple ions. Vm Vm = - 82 mV

  6. Membrane potential changes with ion movement depolarizing stimulus

  7. fig 5-41 • Depolarization:  Vm, ICF becomes more positive • Repolarization: return to resting membrane potential • Hyperpolarization:  Vm; ICF becomes more negative

  8. Summation of graded potentials Graded potential changes can cause action potential

  9. http://www.blackwellpublishing.com/matthews/neurotrans.html

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