The membrane Resting Membrane Potential Animation

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$Microsoft PowerPoint - Intermedier filamentumok [Kompatibilis m\363d]$

Resting Membrane Potential Na + Outside + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - A - K + Cl- 142 mEq/L 4 mEq/L K + 140 mEq/L Cl - Na Inside + 14 mEq/L Resting Membrane Potential Outside A - K + Cl- 142 mEq/L 4 mEq/L K + 140 mEq/L Cl - Na + Na Inside + 14 mEq/L Resting Membrane Potential Outside + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + A - K + Cl- 142 mEq/L 4 mEq/L K + 140 mEq/L Na + Na Inside + 14 mEq/L • Make cell membrane SELECTIVELY permeable to K+ • K+ wants to move toward region of lower concentration (CHEMICAL FORCE to move down concentration gradient) Cl - Resting Membrane Potential Typical: -30 - 90 mV Na + Outside + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - A - K + Cl- 142 mEq/L 4 mEq/L K + 140 mEq/L Cl - Na Inside + 14 mEq/L • If electrode is inserted into cardiac cell, will detect a negative reading compared to outside of the cell of -80mV The electric field strength: 70 mM/5 nm = 140 000 V/cm Resting Membrane Potential Outside A - K + Cl- 142 mEq/L 4 mEq/L K + 140 mEq/L Cl - Na + Na Inside + 14 mEq/L • Make cell membrane SELECTIVELY permeable to K+ • K+ wants to move toward region of lower concentration (CHEMICAL FORCE to move down concentration gradient) Resting Membrane Potential Na + Outside + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - A - K + Cl- 142 mEq/L 4 mEq/L K + 140 mEq/L Cl - Na Inside + 14 mEq/L • As K + leaves cell, negativity increases on the inside of the cell membrane and electrostatically attracts K + . This electrostatic force prevents K + from leaving cell. 2
Resting Membrane Potential Na + Outside + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - A - Chemical driving force is eventually balanced by K + Cl- 142 mEq/L 4 mEq/L K + 140 mEq/L Cl - Nernst Equation chemical potential ⇒ W chem = NRT ln (X1/X2) Na Inside + 14 mEq/L Electrical driving force so no further net movement of K + N = number of moles associated with the concentration gradient R = gas constant T = absolute temperature X1 / X2 = concentration gradient electic potential ⇒ W el = NzF ΔE N = number of moles of the charged particles z = valency F = Faraday’s number ∆E (= E 1-E 2 ) = strength of the electric field (V) € € € Nernst Equation NzFE = NRT ln X 1 X 2 zFE = RT ln X 1 X 2 E = RT zF ln X 1 X 2 Forces controlling the movements of charged particles Chemical potential: (Willard Gibbs (1876) - American mathematical physicist) The chemical potential of a thermodynamic system is the amount of energy by which the system would change if an additional particle were introduced (number of the particles!). Concentration gradient → diffusion: moving the particles from a high concentration area to a low one → diffusion potential. Electric potential: the difference in electrical charge between two points in a circuit expressed in volts. Electrical gradients: An electric field creates a force that can move the charged(+ or -) particles (the work of the electric field) → electric current: moving charged particles. Electro-chemical potential The combination (sum) of the chemical and the electric potential. Related to the average energy affecting the charged particle. A little bit more about the Nernst Equation Nernst Equation The general form of the equation in your textbook: What is the meaning of E x? E x is the potential at which the flux due to diffusion is equal and opposite to the flux due to electrophoresis What is E K for the cell we showed at the beginning? 3
Page 1: Resting Membrane Potential and Acti
Page 5 and 6: Resting Membrane Potential Na + Out
Page 7: Course of the Action Potential •

The membrane Resting Membrane Potential Animation

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