How does a low extracellular potassium concentration affect muscle contraction?

The extracellular potassium concentration is too low, i.e., the tissue fluid and blood potassium are low.

Increase excitability: When the concentration of extracellular potassium or serum potassium decreases, the difference between the potassium concentration inside and outside the membrane increases, and according to the theory, the potassium efflux increases, and the resting potential increases, but in fact, when the blood potassium decreases, the membrane potential decreases instead of increasing. This is because the permeability of the membrane to potassium decreases at low potassium levels, so the membrane potential decreases despite the increase in potassium concentration between the inside and outside of the membrane.

Excitability is increased as the membrane potential decreases close to the threshold potential.

Potassium has the function of maintaining neuromuscular stress, and the neuromuscular system can only normalize stress when a certain concentration of potassium in the blood is maintained. When the concentration of potassium in the extracellular fluid decreases, neuromuscular irritability decreases, and paralysis occurs. Therefore, hypokalemia manifests as muscle weakness and paralysis.

It generally begins in the lower limbs, manifests as difficulty in movement, unsteadiness in standing, and with the aggravation of hypokalemia, muscle weakness can become more severe, and muscle strength in the trunk and upper limbs is also significantly weakened. When the respiratory muscles are affected, respiratory failure can occur. Flat sperm muscle weakness manifests as intestinal paralysis or even paralytic intestinal obstruction muscle weakness, often accompanied by limb numbness, muscle tenderness, and tetany.

I've actually seen it in physiology, it's called "skeletal muscle."

contractile mechanisms and excitation-contraction coupling".

But this is mainly with calcium ions.

Related, if you want to say potassium ions.

I think it should be that the same charge repels each other and affects the coupling, resulting in weakened skeletal muscle excitation and less obvious muscle contraction.

At the same time, I would like to add that if there is more calcium, the muscles will maintain a state of contraction, and if there are fewer calcium ions, the muscles will maintain a state of relaxation.

Hope it helps.

Mom said... Don't go to the hospital if you're sick.

In the resting state, the intracellular potassium concentration is about 30 times that of the extracellular potassium ion, as opposed to the extracellular sodium ion.

The concentration is about 15 times the concentration of sodium ions in the cell. Due to the unbalanced ion distribution on both sides of the membrane and the high permeability of the membrane to K+, a resting potential is formed.

When a pair of measuring microelectrodes are both outside the membrane, there is no potential difference between the electrodes.

The oscilloscope is pierced within the membrane at the tip of a microelectrode.

shows an abrupt change in potential, which indicates a potential difference between the two electrodes, i.e., the cell membrane.

There is a potential difference between the two sides, and the potential inside the membrane is lower than that outside the membrane.

Increasing the concentration of potassium ions in the extracellular fluid decreases the absolute value of the resting potential.

Because the resting potential is mainly formed due to the outflow of potassium ions, and its value is the potential value of potassium ions inside and outside the cell membrane when they move to equilibrium, the resting potential is also called the equilibrium potential of potassium ions, and the equilibrium potential of potassium ions is determined by the concentration difference between potassium ions inside and outside the cell.

The cells are immersed in the interstitial fluid, and only the cell membrane is separated between the two, and water and everything that can pass through the cell membrane can be exchanged between the two.

Elevated extracellular potassium concentrations reduce cellular excitability.

At resting potential, potassium ions flow out, and if the concentration of potassium ions outside the cell increases, the potential difference between the inside and outside of the cell membrane decreases, thereby reducing the excitability of the cell.

Under normal cell conditions, the extracellular high sodium with negative potential, and the intracellular high potassium with positive potential, which is also the case with nerve cells, in the absence of nerve impulse transmission, this balance forms a resting potential. Nerve impulses pass through, and transient extracellular positive potentials, intracellular negative potentials, and large amounts of sodium ions influx appear. Please refer to the Physiology textbook.

When the concentration of extracellular potassium ions is too high, there is a high positive potential outside the cell, which is similar to the situation where nerve impulses persist, and the cell can no longer receive the electrical signal caused by the ion gradient to cause the ascending, and at the same time, the protruding transmitter at the end of the meridian has been continuously released, and there is nothing excess to release. On the other hand, the muscles are already in a state of continuous contraction at this time, and when the neurotransmitters are exhausted, the muscles relax and cannot contract again for a short time.

Under normal circumstances, the concentration of extracellular sodium ions is high, and the concentration of intracellular potassium ions is high, and the potential is positive outside and negative inside. When the extracellular potassium concentration is high, sodium ions cannot flow inward, and cannot be rented into local currents, that is, there is no electrical signal, so there is no confronting Zen filial piety.