Explain How The Permeability Of A Cell Increases Enormously During The Action Potential
B1: The permeability of the cell increases enormously during the action potential. Comte Whitney
Electricity is vital for neural function and communication. The semi-permeable membrane and presence of charged particles in solution (ions), enables the cell to have control of an electric potential.
The cell
The concentrations of Na+ and K+ ions upon either side of a cell’s membrane are not equal. In order for the equilibrium to be restored, sodium will attempt to enter the cell, whilst potassium will exit the cell. It is this movement that is harnessed to generate electricity. However, these ions cannot interact directly with the lipid bi-layer membrane and cross in the desired direction, and thus mechanisms are required to cross the membrane. Therefore the permeability of a cell will increase dramatically …show more content…
The dendrites of a nerve cell receive a stimulus, resulting in the opening of some of the Na+ voltage gated channels (Nav) to open, which when at rest are closed. If this flow of Na+ ions into the cell is sufficient to change the interior potential to from the resting potential of -70mV to approximately -55mV (the threshold) then more of the Nav’s will proceed to open. It is important to note that a large portion of these channels are in the inactive state, and thus, never will all of them be open at the same time and moreover never will the full action potential of +60mV be reached.
2. Once the threshold has been reached and the Na+ channels have opened, the influx of Na+ ions into the cell causing the interior potential to reach its peak. The number of Navs that were opened determines this peak, and in the case of figure (2) this maximum point was at +30mV. This phase is known as depolarisation. Furthermore, the more the cell is depolarised, the more permeable it will be to
Electricity is vital for neural function and communication. The semi-permeable membrane and presence of charged particles in solution (ions), enables the cell to have control of an electric potential.
The cell
The concentrations of Na+ and K+ ions upon either side of a cell’s membrane are not equal. In order for the equilibrium to be restored, sodium will attempt to enter the cell, whilst potassium will exit the cell. It is this movement that is harnessed to generate electricity. However, these ions cannot interact directly with the lipid bi-layer membrane and cross in the desired direction, and thus mechanisms are required to cross the membrane. Therefore the permeability of a cell will increase dramatically …show more content…
The dendrites of a nerve cell receive a stimulus, resulting in the opening of some of the Na+ voltage gated channels (Nav) to open, which when at rest are closed. If this flow of Na+ ions into the cell is sufficient to change the interior potential to from the resting potential of -70mV to approximately -55mV (the threshold) then more of the Nav’s will proceed to open. It is important to note that a large portion of these channels are in the inactive state, and thus, never will all of them be open at the same time and moreover never will the full action potential of +60mV be reached.
2. Once the threshold has been reached and the Na+ channels have opened, the influx of Na+ ions into the cell causing the interior potential to reach its peak. The number of Navs that were opened determines this peak, and in the case of figure (2) this maximum point was at +30mV. This phase is known as depolarisation. Furthermore, the more the cell is depolarised, the more permeable it will be to