Potential Action and Potential Cell Membrane Mechanisms

One part of the cell found outside is the cell membrane. This section functions as a barrier or barrier between cells and their external environment. In addition to the main function as a wrapper, the membrane also functions as a very selective filter, a tool for active transport, controlling the entry of nutrients and the release of metabolic results, maintaining ionic concentrations outside the cell and also as sensors for signals outside the cell.

This constituent component of cell membranes consists of phospholipids, proteins, oligosaccharides, glycolipids, and cholesterol. There are three types of lipid molecules found in membranes, namely phospholipid, cholesterol, and glycolipid. The function of the three lipids is as a membrane function which plays a role in its function to be sensitive to water molecules (hidrophilic and hidrophopbic). The probable protein cluster is in the lipid bilayer, which functions as an active transport of certain molecules, as an enzyme that functions to catalyze, and can also be a link between the structure of the plasma membrane and the cytoskeleton or matrix with adjacent cells.

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The specifications of the constituent components of cell membranes are mostly related to the transport function of substances, creating a lot of membrane traffic. Membrane traffic is classified into two ways, namely by passive transport to move molecules without special mechanisms and active transport to move molecules with special mechanisms (with the help of several protein functions).

Most of these transport functions will produce cell activity where this cell activity will focus on the state of polarization being depolarized and returning to polarization again accompanied by changes in the potential of cell membranes. These changes can also result in a change in the negative state of a cell membrane, the change can change from negative to positive and then return to negative again. This change will produce a voltage impulse called an action potential. The mechanism of action potential is as follows:

Stage of Polarization

It is the stage of the resting membrane potential before the action potential. On a negative membrane of -900 mV. In a cell even though in a state of rest there is still a potential difference between the two sides of the membrane

Depolarization Phase

If the resting cell is given an adequate level of stimulation, the cell will change to active state. In the active state cell membrane potential changes from negative to positive on the inside. This condition is called depolarization. This event starts from a point on the surface of the membrane and will propagate to the entire surface of the membrane.

At this stage the membrane is very permeable, very reactive to Na + ions so that the Na + channel is opened so that Na + will enter into so that the membrane potential increases so that overshoot occurs if the potential is above 0.

Repolarization Phase

In a state of repolarization, the membrane potential changes from positive on the inside to returning to the negative on the inside. The stages of repolarization begin from a point and propagate to the entire surface of the cell membrane. If the entire cell membrane has a negative charge on the inside, then the cell is said to be in a state of rest or a state of polarisai back and ready to receive the next stimulus.

At this stage the Na + channel starts to close, the K + ion channel opens and the K + ion exits so that the potential membrane returns to the resting phase.

Hyperpolarization stage

If repolarization is excessive, the state of the membrane potential is below the normal value so that the Na + and K + ions return to normal and the membrane has finished transporting the substance.

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Author: Andrei Suprayogi

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