>In resting state,
membrane is permeable to K+ and relatively impermeable to Na+.
>When a stimulus depolarize the membrane into the threshold value the voltage gated Na+ channels open, vastly increasing the membrane’s permeability to Na+.
>Na+ enters the cell across the membrane under the influence of both concentration gradient and the electric gradient.
>Na+ makes the membrane more depolarized and that makes more voltage gated sodium channels to open.
>As the membrane potential approaches equilibrium potential of Na+ the driving force of Na+ is reduced. Therefore less number of Na+ reach into the cell.
>After a short time the voltage gated Na+ channels are inactivated and stop the taken in of the Na+. Here the membrane potential rise to +45mV.
>As this occurs, the voltage gated K+ channels open and greatly increases the permeability to K+ ions. Therefore K+ leaves the cell under the influence of concentration gradient and electric gradient.
>As K+ leaves, the positive charge inside the cell is reduced. After awhile the equilibrium potential of K+ is obtained and the membrane is hyperpolarized. Now the membrane potential is -75mV. Hyperpolarization is due to the delay of closing the K+ channels compared to Na+ channels.
>The voltage gated K+ channels close and by then the Na+ channels recovered by inactivation.
>When a stimulus depolarize the membrane into the threshold value the voltage gated Na+ channels open, vastly increasing the membrane’s permeability to Na+.
>Na+ enters the cell across the membrane under the influence of both concentration gradient and the electric gradient.
>Na+ makes the membrane more depolarized and that makes more voltage gated sodium channels to open.
>As the membrane potential approaches equilibrium potential of Na+ the driving force of Na+ is reduced. Therefore less number of Na+ reach into the cell.
>After a short time the voltage gated Na+ channels are inactivated and stop the taken in of the Na+. Here the membrane potential rise to +45mV.
>As this occurs, the voltage gated K+ channels open and greatly increases the permeability to K+ ions. Therefore K+ leaves the cell under the influence of concentration gradient and electric gradient.
>As K+ leaves, the positive charge inside the cell is reduced. After awhile the equilibrium potential of K+ is obtained and the membrane is hyperpolarized. Now the membrane potential is -75mV. Hyperpolarization is due to the delay of closing the K+ channels compared to Na+ channels.
>The voltage gated K+ channels close and by then the Na+ channels recovered by inactivation.
Useful information thanks for your post.
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