Action Potential Generation

Action potential generation the plasma membrane of a neuron separates the extracellular space from the intracellular space sodium ions are found in high concentration outside of the cell whereas potassium ions are found in high concentration inside of the cell. Voltage-gated sodium channels, sodium potassium ATP-ase pumps and voltage-gated potassium channels are found embedded in the plasma membrane of the neuron. To initiate an action potential a stimulus causes the wave a positive charge to reach voltage-gated sodium channels on the neuron membrane. The increase in positive charge causes the voltage-gated sodium channels to open. Positively charged sodium ions flood into the neuron following their concentration gradient this causes the inside a membrane near to the open sodium channel to become more positively charged this process is the deep polarization of the cell membrane The build up a positive charge on the inside of the membrane eventually causes the voltage-gated sodium channels to close. At the same time voltage-gated potassium channels open since open only when the inside remember is that maximum positive charge. Positively charged potassium ions flow rapidly out of the neuron following their concentration gradient this decreases the level of positive charge on the inside surface of the neuron. This return of the membrane to resting levels of negative charge is called repolarization. Once the region and the membrane has been fully repolarized, potassium channels close a sodium/potassium pump uses ATP energy to restore the concentration gradient and put potassium and sodium to the resting values Let's summarize the processes of generating an action potential resting potential is the membrane potential of a neuron when it is at rest. The resting potential is well below zero to initiate an action potential the stimulus causes a slight depolarization or increase in positive charge. If the stimulus is strong enough to cause the membrane potential to reach a certain threshold action potential will begin. In the rising phase of an action potential wilted kid sodium channels open and sodium ions flow into the cell this causes voltage to increase inside the cell During the following phase of the action potential voltage-gated sodium channels close, voltage-gate potassium channels open the opening of the potassium channels causes potassium ions to diffuse out of the cell rapidly causing a sharp decrease in voltage. During the recovery phase sodium potassium ATP-ase pump restores the resting potential sodium potassium ATP-ase pumps pump 2 sodium ions in and 3 potassium ions out of the neuron. Sodium potassium ATP-ase pumps require ATP to function