In the quiet state, the channel through which the cell membrane is permeable to k belongs to the vol

1. Why is the permeability of the cell membrane to positive ions K higher in the resting stateWhen nerve cells are in a resting state, the Na+, K+ channels are closed, sodium ions and potassium ion channels are inhibited, and there are a large number of sodium ions outside the cell, while a large number of negative ions (mainly chloride ions) and some potassium ions are left in the cell The resting potential charge distribution is positive and negative on the outside, and the main reason for the occurrence is caused by the outflow of K+, indicating that the nerve cell membrane is more permeable to potassium ions

The resting potential is the positive and negative potential formed by the cell membrane of a neuron. In the resting state, the potassium ion channels on the cell membrane of neurons are more open, while the sodium and chloride ion channels are basically closed, so the cell membrane of neurons at this time is mainly permeable to potassium ions, that is, potassium ions can diffuse across the membrane, so potassium ions can establish their own equilibrium potential. On the other hand, sodium and chloride ions are less permeable and are not easy to diffuse across the membrane, and it is not easy to form an equilibrium potential (but it will also have an impact on the resting potential).

Therefore, the resting potential formed in the resting state is closer to the equilibrium potential of potassium ions, and the magnitude of the resting potential is mainly affected by potassium ions, and the influence of sodium ions and chloride ions on the resting potential is very small and negligible. This is the reason why we say that the resting potential is only affected by potassium ions.

Resting potential spine trouser disturbance.

The basic cause is the transmembrane diffusion of ions, which is also related to the characteristics of the sodium-potassium pump. Cell membrane.

The concentration of K+ in the inner cell is higher than in the extracellular. In the quiet state, the membrane is permeable to K+, and the concentration difference of K+ diffuses to the outside of the membrane, and the protein anion in the membrane cannot pass through the membrane and is blocked in the membrane, resulting in an increase in the positive charge outside the membrane and a positive potential. The negative charge in the membrane increases relatively, and the potential becomes negative, resulting in the potential difference between the inside and outside of the membrane.

This potential pure dismantling prevents further outflow of K+, and when the two opposing forces, the concentration difference of K+ outflow and the potential difference that prevents K+ outflow, are in phase, etc., the outflow of K+ stops. The potential difference between the inside and outside of the membrane is maintained in a stable state, i.e., the resting potential.

RP: The generation of resting potential is mainly formed outside K, but also a small amount of NA influx and electrogenesis of the sodium-potassium pump are involved.

AP: The upward history of the action potential is mainly due to the rapid influx of a large amount of NA after the activation of the voltage-gated NA channel. The descending branch is the result of the inactivation of the voltage-gated NA channel, which stops the NA inflow, and the rapid flow of K after the activation of the voltage-gated first K channel.

The first question is that you can get in or out. Permeability is membrane conductance. The greater the permeability, the greater the membrane conductance, and the stronger the current when the channel is open. Conversely, the current is weak.

As for whether an ion is inflow or outflow, it depends on the algebraic sum of the difference in ion concentration between the two sides of the membrane and the potential difference resulting from the ion charge, which is called the electrochemical gradient. The second problem is very complicated, simply put, hypokalemia, the difference between potassium ion concentration inside and outside the membrane increases, and the potassium efflux increases, the negative value of EM resting potential increases, and the cell excitability decreases; Conversely, the negative EM value decreases and the excitability increases. The third question about ECG is complicated.

Hypokalemia shows that the resting potential level is shifted downward, but because hypokalemia can reduce potassium channel conductance, the result is a slight depolarization of the membrane potential, and the excitability of cardiomyocytes (manifested in Purkinje fibers) is actually increased; Therefore, automaticity is elevated and conductivity is decreased. The most obvious feature of the ECG is that the T wave is low or even inverted, and the U wave may occur (the mechanism of this generation is not clear). Hyperkalemia, the high level of cardiomyocyte depolarization, but affects the membrane reactivity of sodium channels, so that the threshold potential rises, and because high potassium increases potassium channel conductance, it can increase excitability (sometimes the total effect is a decrease in excitability, because the increased potassium conductance is not as strong as the decrease in sodium conductance), then the conductivity decreases, and because the membrane potential level is raised, the opening probability of hyperpolarization-sensitive inward cation channels (pacing current, mainly in Purkinje fibers, sinus node has little effect) is reduced, and the automaticity is reduced.

ECG overall block, prolonged PR interval, widened QRS complex, prolonged QT interval, and elevated T wave (the mechanism is not well understood).

To give you a note, the NA channel on the cell membrane is usually inactive, only the K channel is always open, the K channel is not inactive, and the NA channel is only open when excited.

The influx of NA is transient current to cell depolarization ik ik1....Talking too much ...

Cell membranes are permeable to sodium. The gradient of sodium ions inside and outside the cell membrane creates a potential difference in sodium. This potential difference drives sodium ions inward through the cell membrane. In the resting state, it is balanced with the sodium-potassium pump.