Lähettiaineiden

Lähettiaineet, also known as neurotransmitters, are chemical messengers that transmit signals across a synapse from one neuron to another neuron, or to a target cell such as a muscle or gland cell. They are essential for communication within the nervous system, enabling a wide range of bodily functions, including mood, sleep, appetite, and muscle movement.

The process begins when an electrical impulse, called an action potential, travels down the axon of a neuron. Upon reaching the axon terminal, this impulse triggers the release of neurotransmitters into the synaptic cleft, the small gap between neurons. These neurotransmitters then diffuse across the cleft and bind to specific receptors on the postsynaptic neuron or target cell. This binding can either excite or inhibit the receiving cell, influencing its activity.

There are many different types of neurotransmitters, each with distinct roles and effects. Some well-known examples include acetylcholine, which plays a role in muscle contraction and learning; dopamine, associated with reward and motivation; serotonin, involved in mood regulation; and glutamate, the most abundant excitatory neurotransmitter in the central nervous system.

The action of neurotransmitters is carefully regulated. After transmitting their signal, they are either broken down by enzymes or reabsorbed by the presynaptic neuron, a process called reuptake, to terminate the signal and allow for the next impulse. Imbalances in neurotransmitter levels or function are implicated in various neurological and psychiatric disorders, highlighting their critical importance for health and well-being.