Potassium spatial buffering
Encyclopedia
Potassium Spatial Buffering is a mechanism for the regulation of extracellular potassium
concentration by astrocyte
s.
The depolarization
of neuron
s tends to raise potassium concentration in the extracellular fluid. If a significant rise occurs, it will interfere with neuronal signaling by depolarizing neurons. Astrocytes have large numbers of potassium ion channels facilitating removal of potassium ions from the extracellular fluid. They are taken up at one region of the astrocyte and then distributed throughout the cytoplasm
of the cell, and further to its neighbors via gap junction
s. This keeps extracellular potassium at levels that prevent interference with normal propagation of an action potential
.
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
concentration by astrocyte
Astrocyte
Astrocytes , also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord...
s.
The depolarization
Depolarization
In biology, depolarization is a change in a cell's membrane potential, making it more positive, or less negative. In neurons and some other cells, a large enough depolarization may result in an action potential...
of neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
s tends to raise potassium concentration in the extracellular fluid. If a significant rise occurs, it will interfere with neuronal signaling by depolarizing neurons. Astrocytes have large numbers of potassium ion channels facilitating removal of potassium ions from the extracellular fluid. They are taken up at one region of the astrocyte and then distributed throughout the cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
of the cell, and further to its neighbors via gap junction
Gap junction
A gap junction or nexus is a specialized intercellular connection between a multitude of animal cell-types. It directly connects the cytoplasm of two cells, which allows various molecules and ions to pass freely between cells....
s. This keeps extracellular potassium at levels that prevent interference with normal propagation of an action potential
Action potential
In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and...
.