närvisignaali

Närvisignaal, also known as a nerve impulse or action potential, is an electrical or electrochemical impulse that travels along a nerve fiber. This signal is the fundamental way in which the nervous system communicates information throughout the body. When a neuron is stimulated, it triggers a rapid change in the electrical potential across its cell membrane. This change, the action potential, propagates down the axon of the neuron like a wave.

The generation of a närvisignaal involves the movement of ions, primarily sodium (Na+) and potassium (K+), across the neuron's membrane through specialized protein channels. Initially, there is a resting potential, where the inside of the neuron is more negative than the outside. Upon stimulation, sodium channels open, allowing sodium ions to rush into the cell, making the inside positive. This depolarization phase quickly triggers the opening of potassium channels, allowing potassium ions to flow out, repolarizing the membrane and restoring the negative charge inside.

This all-or-none event ensures that the signal is transmitted without losing strength. Once the närvisignaal reaches the end of the axon, it triggers the release of neurotransmitters into the synaptic cleft, which then bind to receptors on the next neuron or target cell, continuing the communication process. Närvisignaalid are crucial for everything from muscle movement and sensory perception to complex thought processes and emotional responses.