What Is Hyperpolarization?

Hyperpolarization refers to a physiological state of the nerve cell membrane. The potential in the membrane is greater than 70 mV, reaching 80 mV, or even 90 mV. The process can make neurons in a temporarily inhibited state. Presented in two forms of post-hyperpolarization potential and inhibitory post-synaptic potential.

Hyperpolarization

Definition: the internal potential of the cell membrane develops in the negative direction, and the external potential

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Cell hyperpolarization is a kind of cell bioelectric phenomenon, which refers to the phenomenon that the value of the potential difference between the inside and outside of the membrane after the signal or stimulation of the cell membrane changes to the direction of increasing the negative value in the membrane. It is important in cell signaling use.

Cell hyperpolarization is a type of bioelectric phenomenon.
The bioelectric phenomenon is generated by cells, and is based on the uneven distribution of charged ions on both sides of the cell membrane and the selective transport of ions across the membrane.
There are two main manifestations of the bioelectrical phenomenon of cell membranes, namely resting potentials at rest and changes in membrane potentials (including local and action potentials) when stimulated.

Since the cell membrane is most permeable to potassium ions when it is quiet, it causes positively charged potassium ions to flow out, so that macromolecules with negatively charged protein ions are blocked from flowing out of the cell membrane, so they are formed in the cell membrane. Negative potential, which is the resting potential.

The resting potential is characterized by positive outside and negative inside, and the most important thing is the negative potential inside the membrane. If on this basis, negatively charged ions in extracellular fluid move into the cell, such as negatively charged chloride ions, The movement of chloride ions into the cell increases the negative charge in the cell, which causes the cell to become hyperpolarized. If the cell is hyperpolarized, it deviates from the direction of the action potential, so the cell appears to be inhibited. For example: the transmission of excitement at the nerve-muscle junction. When the neuronal encapsulation is excited, the excitement is transmitted to the nerve endings in the form of action potentials. When it is transmitted to the synaptic bodies of the nerve endings, it will cause the release of neurotransmitters. If inhibitory transmitters, such as dopamine, are released from nerve endings or protruding vesicles, binding to the corresponding receptors on the nerve-muscle junction membrane will lead to increased permeability of the membrane to the chloride ion after the junction, ie The opening of the chloride ion channel on the membrane after the joint promotes the movement of chloride ions into the muscle cell membrane, which will increase the negative charge in the muscle cells of the membrane after the joint, causing the cells to become hyperpolarized, and the occurrence of hyperpolarization will cause the muscle cells to be in The suppressed state cannot shrink.

If on the basis of the resting potential, when the cell is effectively stimulated, the sodium ion channels on the cell membrane will be opened, leading to the inward flow of sodium ions, the sodium ions will have a positive charge, and the negative charge in the cell membrane will be neutralized when entering the cell membrane. The negative electrical charge in the cell membrane is reduced, that is, the cell is depolarized, and the occurrence of depolarization lays the foundation for the action potential to explode. If the depolarization can reach the threshold potential of the cell membrane, it will inevitably lead to the occurrence of action potentials. Once the action potential of the cell membrane occurs and spreads throughout the cell membrane, the cells will be excited. Such as the transmission of excitement at the nerve-muscle junction, when the excitement is transmitted to the protruding bodies of nerve endings in the form of nerve impulses, that is, action potentials, if the protruding vesicles release excitatory transmitters such as acetylcholine, acetylcholine and the posterior membrane of the joint That is, the M receptor of the endplate of the exercise binds, so that the sodium ion channels on the membrane after the joint are opened, and sodium ion inflow occurs, and the membrane after the joint is depolarized to form the endplate potential, which is finally spread on the muscle cell membrane through spreading. The action potential bursts on the muscle cells, causing muscle cells to excite and contract and relax.

From the above examples, it can be seen that the occurrence of hyperpolarization and depolarization is mainly due to the opening of different ion channels on the cell membrane, which causes different charged ions to move across the membrane, which causes the positive and negative charges in the cell membrane to increase or decrease, resulting in membrane potential. Changes, and changes in membrane potential determine the functional state of the cell, that is, excited or inhibited.

The occurrence of depolarization is a prerequisite for cell excitement, and action potential is a sign of cell excitement. The occurrence of hyperpolarization is the prerequisite for cell inhibition. It is opposite to the direction of the depolarized membrane potential change, which deviates from the direction in which the action potential occurs, so the cell cannot be excited and is inhibited. The contraction of skeletal muscles, the secretion of glands, the conduction of nerves, and the pumping of blood from the heart muscle are all based on the preferential action potential of cell membranes.