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Across 4. Channels which are active and ions can flow through rapidly 7. ___________ ions are at high concentration outside the neuron 8. The outside of a neuron is relatively _________ (positive or negative) 11. Which type of potential occurs over short distances and degrades quickly? 13. Channels which are passive and ions can move through slowly 16. An active Na+/K+ _____ is required to prevent equilibrium between the inside and outside of the neuron 17. Event which causes the membrane potential to become less negative 18. Difference in the amount of charge between two points 20. ___________ ions are at a high concentration inside the neuron 23. The cell membrane is more permeable to which ion? 25. Hindrance of the medium to the flow of electricity 26. The inside of a neuron is relatively _________ (positive or negative) 27. ___________ gated channels open in response to a specific chemical

Down 1. Event which causes the membrane potential to becomes more negative 2. Which type of potential occurs when the membrane is only slightly depolarized 3. What is the voltage threshold for an action potential to be generated? 5. Measure of the potential energy in an electrical system 6. ___________ gated channels open in response to a sufficient amount of electrical current 9. Action potential step where excess potassium leaving the cell causes the voltage to drop below -70mv 10. ___________ gated channels open in response to a physical stimulation 12. Action potential step where potassium gates open, so that potassium ions quickly leave the neuron 14. Action potential step where potassium gates and sodium activation gates are closed, but sodium inactivation gates are open 15. Flow of an electrical charge from one area to another 17. Action potential step where sodium activation gates open, so that sodium ions quickly enter the neuron 19. At what voltage during depolarization do sodium inactivation gates close? 21. Biological electricity is caused by ______. 22. Which type of potential occurs over long distances and does not degrade quickly? 24. What is the voltage of the resting membrane potential?