Närvivahendaja

Närvivahendaja, also known as a neurotransmitter, is a chemical substance that transmits nerve impulses between neurons or between a neuron and a target cell, such as a muscle or gland cell. These molecules are released from the presynaptic neuron into the synaptic cleft, the small gap between neurons, and then bind to specific receptors on the postsynaptic neuron or target cell. This binding initiates a response in the receiving cell, either excitatory, causing it to become more likely to fire an action potential, or inhibitory, making it less likely.

There are numerous types of närvivahendajad, each with distinct chemical structures and functions. Some common examples include acetylcholine, which plays a role in muscle contraction and learning; dopamine, associated with reward and motivation; serotonin, involved in mood and sleep regulation; and norepinephrine, which mediates the body's response to stress. The balance and proper functioning of these chemical messengers are crucial for a wide range of physiological and psychological processes. Dysregulation of närvivahendajad is implicated in various neurological and psychiatric disorders.