närviimpulsiks

Närviimpulsiks, also known as a nerve impulse or action potential, is the fundamental electrical signal that neurons use to communicate with each other. It is a rapid, transient change in the electrical potential across the cell membrane of a neuron. This change is initiated when a stimulus, such as a sensory input or a signal from another neuron, causes the neuron's membrane to become depolarized.

Depolarization occurs when ion channels in the cell membrane open, allowing positively charged ions, primarily sodium ions, to rush into the neuron. This influx of positive charge makes the inside of the neuron more positive relative to the outside. If the depolarization reaches a certain threshold, it triggers an action potential.

The action potential then propagates along the axon, the long projection of the neuron, like a wave. During propagation, the membrane rapidly repolarizes as potassium ions flow out of the neuron, restoring the negative charge inside. This sequence of depolarization and repolarization allows the electrical signal to travel quickly from one end of the neuron to the other.

Once the nerve impulse reaches the end of the axon, it triggers the release of neurotransmitters into the synapse, the small gap between neurons. These neurotransmitters then bind to receptors on the next neuron, potentially initiating a new nerve impulse in that neuron, thus continuing the communication chain. This entire process is crucial for all nervous system functions, from sensory perception and motor control to thought and emotion.