neurotransmitterszoals

Neurotransmitters are chemical messengers that transmit signals across synapses between neurons and other cells. They are released from presynaptic terminals in response to an action potential and bind to receptors on the postsynaptic cell, producing excitatory or inhibitory effects that influence neural circuits and a range of physiological processes such as movement, sensation, and mood.

Classification of neurotransmitters includes small-molecule transmitters, such as acetylcholine, glutamate, and GABA, and biogenic amines, including dopamine, norepinephrine, and serotonin. Neuropeptides form another broad class, consisting of short chains of amino acids. Some unconventional transmitters, such as nitric oxide, act by diffusing through membranes rather than binding to traditional receptors.

Release and action: When an action potential reaches the nerve terminal, calcium ions enter and trigger vesicle fusion, releasing neurotransmitters into the synaptic cleft. They diffuse to receptors on the postsynaptic membrane, which may be ligand-gated ion channels or G protein-coupled receptors, producing rapid excitatory or slower modulatory effects that shape neuronal signaling.

Termination: Neurotransmission ends mainly by reuptake into the presynaptic neuron, enzymatic degradation in the synaptic cleft, or diffusion away from the site of action. Reuptake and degradation help regulate signal duration and prevent excessive neurotransmitter activity.

Clinical and functional relevance: Proper neurotransmitter signaling is essential for movement, cognition, emotion, and autonomic regulation. Imbalances or receptor dysfunction are associated with disorders such as Parkinson's disease (dopamine deficit), depression and anxiety (serotonin and norepinephrine), epilepsy (glutamate and GABA imbalance), and schizophrenia (dopamine and glutamate dysregulation). Neurotransmitters zoals acetylcholine, dopamine, and serotonin illustrate the diversity of chemical signaling in the nervous system.