Välittäjämolekyylit

Välittäjämolekyylit, or neurotransmitters, are chemical messengers that transmit signals across a synapse from one neuron to another. These molecules play a crucial role in virtually all aspects of brain function and behavior, including thought, emotion, movement, and sensory perception. They are synthesized in the presynaptic neuron and stored in vesicles. When an electrical impulse reaches the axon terminal, these vesicles fuse with the presynaptic membrane, releasing the neurotransmitters into the synaptic cleft.

Once released, neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic neuron. This binding event can either excite or inhibit the postsynaptic neuron, depending on the type of neurotransmitter and receptor. Excitatory neurotransmitters depolarize the postsynaptic membrane, making it more likely to fire an action potential, while inhibitory neurotransmitters hyperpolarize the membrane, making it less likely to fire.

Common neurotransmitters include acetylcholine, dopamine, serotonin, norepinephrine, GABA, and glutamate. Each of these has distinct roles and distributions within the nervous system. For instance, acetylcholine is involved in muscle contraction and learning, dopamine in reward and motivation, and serotonin in mood regulation. The precise balance and function of these molecules are essential for maintaining healthy neurological processes. Dysregulation of neurotransmitter systems is implicated in various neurological and psychiatric disorders, such as depression, Parkinson's disease, and schizophrenia.