Brief information about bioelectrical phenomena

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Every living cell is like a galvanic element is the generator of electric current. All its activity is connected with the electric phenomena that are currently due to improvements electrophysiological methods give a fairly accurate study. Substantial assistance in the investigation of a number of electric phenomena in living cells had microelectrodes, representing made of refractory thick-walled glass capillaries 1 mm diameter with drawn ends (the diameter from 0.5 to 0.1 microns) and filled 2.5 M solution KS1. These electrodes can be entered into the cell without causing it any harm.
If two such microelectrode, United with the sensitive measuring device, be applied to any two points on the outer surface of the cell membrane, the arrow of the instrument will not be rejected: it means, that different points of the outer surface of the cell membrane is no potential difference exists. But if one of microelectrodes to enter into the cell, the arrow will be rejected: between the outer and inner surfaces of the cell membrane potential difference exists (often referred to as the resting potential). It is easy to verify that this difference appears in the moment when microelectrode passes through the surface of cells and concerns of protoplasm. In further promoting electrode through the protoplasm potential difference does not change; it will disappear only after the electrode out of the cell through the opposite surface.
Different cells of varying the resting potential. It usually ranges from 50 to 100 millivolts (mV). The outer surface of the membrane is charged positively, internal - negative. Membrane potential exists only as long as the cell alive. With the death disappears and the potential difference between the surfaces of the membrane.
If any one of a membrane can cause irritation of certain forces, the cell from the state of rest goes into an active state, and charges membrane in place irritation change their sign. Exposed to irritation of the area of the outer surface of the membrane becomes negatively charged against the corresponding section of the inner surface (this potential difference was called action potential). Such a change of the sign of the charges in the transition to active status is defined in all cells that are able under the influence of irritation proper intensity to move into an active state - excitation. Changes in the electric state in place of irritation does not last long, on average, about 1 millisecond (MS), and then quickly revert to their original state (the resting potential). Having arisen in one place, excitement quickly spreads across the cells, with each site in the course of propagation of an excitation occurs described changes of electric charges and their subsequent recovery.
Relevant dimensions shown that the action potential is not only the opposite direction, but 30-50 mW more resting potential. This means that during the transition cells in active state, it first complete depolarization of the membrane, i.e. the disappearance of the rest potential due to the discharge of the surfaces of the membrane, and then recharge.
Thus, the transfer of cells from one state to another, usually accompanied by a well-defined electric phenomena. You cannot, for example, cause the stimulation of the cells without a corresponding change characters charge on the surface of the membrane. Conversely, if using an external power source change the signs of the charges on the cell membrane (positive electrode to enter into the cell and negative applied to the outer surface) and cause at least a partial its depolarization (15-20 mW),- in the cage will experience the excitement that is going to spread.
What underlies observed in excitable cells of electric phenomena? It is well known that almost all physical and chemical processes in nature accompanied by certain electrical phenomena. In the same living cells of the physical and chemical processes occur continuously. The main role in the emergence of electric charges in the cage play, according to popular opinion, ion processes (just as it is observed in the galvanic elements). The source of ions in the cell are salts. As shown by numerous studies, the cells contain 80% of water and 1.5% salts, mainly potassium and calcium. One of the distinguishing features of a living cell is a significant difference in the composition and concentration of ions in the content of the cell and its environment. For most of the cells characterized by high internal concentration of potassium and low in sodium concentration. The content of potassium in the cell is 0.4%, while in environmental cage environment potassium contains only 0,13%. Sodium same in the cell of 0.08%, while in the environment - 0,85%. This peculiarity of the chemical composition of cells and the environment characteristic of almost all living organisms. After their death the difference in the concentration of potassium and sodium ions inside and outside the cell is aligned (by the laws of diffusion).