PHYSIOLOGY
SYNAPTIC PHYSIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Electrical
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Chemical
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Either A or B
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None of the above
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Detailed explanation-1: -Second, the voltage-gated potassium channels open (the delayed-rectifier potassium channels). The driving force pushes potassium out of the cell, causing the membrane potential to become negative again.
Detailed explanation-2: -Thus, the driving force acting on K+ is: DFK = −65 − −90 = +25 mV. The sign of the driving force is positive. Since K+ is a positively charged ion (cation), a positive value for the driving force indicates that K+ is flowing out of the cell (under these conditions).
Detailed explanation-3: -The membrane is permeable to K+ at rest because many channels are open. In a normal cell, Na+ permeability is about 5% of the K+ permeability or even less, whereas the respective equilibrium potentials are +60 mV for sodium (ENa) and −90 mV for potassium (EK).
Detailed explanation-4: -However, the cell membrane is much more permeable to potassium ions than to it is to sodium ions. As a result, potassium ions diffuse out of the cell more rapidly than sodium ions enter the cytoplasm.