Hyperpolarization

Hyperpolarization (pronunciation: /ˌhaɪ.pərˌpoʊ.lər.aɪˈzeɪ.ʃən/) is a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization. It inhibits action potentials by increasing the stimulus required to move the membrane potential to the action potential threshold.

Etymology

The term "hyperpolarization" is derived from the Greek words "hyper" meaning over or above and "polarize" which refers to the creation of polarity or difference in electric potential.

Mechanism

Hyperpolarization is often caused by efflux of K+ (potassium ions) out of the cell. More potassium ions moving out of the cell than sodium ions moving in makes the inside of the cell more negative relative to the outside. This increases the magnitude of the electrochemical gradient for those ions' movement.

Role in Neurons

In neurons, hyperpolarization is a decrease of the membrane potential from the resting potential, reducing the neuron's ability to generate an action potential. The hyperpolarization is the part of the inhibitory post-synaptic potential (IPSP).

Related Terms

• Depolarization
• Action potential
• Neurons
• Inhibitory post-synaptic potential (IPSP)

See Also

• Membrane potential
• Electrochemical gradient

External links

• Medical encyclopedia article on Hyperpolarization
• Wikipedia's article - Hyperpolarization

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