Närvisignaalidel

Närvisignaalidel, also known as nerve impulses or action potentials, are rapid electrical and chemical changes that travel along the membrane of a nerve cell (neuron). These signals are the fundamental way in which the nervous system communicates information throughout the body, enabling everything from thought and sensation to movement and vital bodily functions.

The process begins when a neuron receives a stimulus, which can be external (like touch or light) or internal (like a signal from another neuron). If the stimulus is strong enough to reach a threshold, it triggers a cascade of events. This involves the rapid opening and closing of ion channels in the neuron's cell membrane. Positively charged ions, primarily sodium (Na+) and potassium (K+), flow into and out of the cell, causing a temporary reversal of the electrical charge across the membrane. This electrical disturbance is the action potential.

This electrical change is self-propagating, meaning it triggers the same electrical change in the adjacent section of the neuron's membrane, and so on, allowing the signal to travel along the axon, which is the long projection of a neuron. At the end of the axon, the electrical signal is converted into a chemical signal. This involves the release of neurotransmitters, chemical messengers, into a small gap called the synapse. These neurotransmitters then bind to receptors on the next neuron, potentially triggering a new nerve impulse in that cell, thus continuing the communication chain. This complex interplay of electrical and chemical signaling is essential for all neural functions.