repolarization
sodium-potassium pump
The chief positive intracellular ion in a resting neuron is a potassium ion. Just inside the cell of a resting neuron, the membrane is negative.
Membrane potential - a nerve cell set and ready to fire;"The wave of reverse polarity" i.e. sodium versus potassium trans-cell-membrane ion passaging - a nerve cell firing; andRecharge period - the regeneration time.
potassium ions
The main ions found inside a neuron are potassium and organic anions. The organic anions cannot cross the cell membrane but potassium ions can. It is the diffusion of potassium ions out of the cell which is the main cause of the resting membrane potential.
Potassium ions (K+) are found in high concentration inside the neuron compared to outside. This concentration gradient is maintained by the sodium-potassium pump.
A neuron that is polarized is also at rest potential. At this stage it is not conducting an impulse and has sodium ions on the outside and potassium ions on the inside.
The period of repolarization of a neuron corresponds to the time when potassium ions move out of the neuron, allowing the cell to return to its resting potential. This phase follows the peak of the action potential when sodium channels close and potassium channels open, leading to membrane potential restoration. Repolarization is essential for the neuron to be able to generate subsequent action potentials.
The chief positive intracellular ion in a resting neuron is potassium (K+). At rest, the neuron has a higher concentration of K+ inside its cell membrane compared to outside. This creates a negative membrane potential, which is crucial for maintaining the resting state of the neuron.
Neuron plasma membranes are most permeable to potassium ions (K+) due to the presence of leak potassium channels. This allows for the resting membrane potential to be closer to the equilibrium potential for potassium. Sodium ions (Na+) and chloride ions (Cl-) also play roles in membrane potential, but potassium ions have the highest permeability.
As potassium leaves the neuron, the inside of the cell will become progressively more negative, which will attract the positive potassium ions, preventing further exodus. If this electrical force is great enough, it will actually draw potassium ions from the outside of the cell back inside.
The sodium-potassium pump is responsible for maintaining the resting membrane potential of a neuron by actively pumping sodium ions out of the cell and potassium ions into the cell, against their concentration gradients. This creates an imbalance of ions across the membrane, contributing to the resting potential of the neuron.