Organelle consisting of a membrane structure that encloses a quantum of neurotransmitter.
First neurotransmitter discovered in the peripheral and central nervous systems; activates skeletal muscles in the somatic nervous system and may either excite or inhibit internal organs in the autonomic system.
nitric oxide (NO)
Gas that acts as a chemical neurotransmitter-for example, to dilate blood vessels, aid digestion, and activate cellular metabolism.
Learning behavior in which a response to a stimulus weakens with repeated stimulus presentations.
Embedded membrane protein that acts as (1) a binding site for a neurotransmitter and (2) a pore that regulates ion flow to directly and rapidly change membrane voltage.
Membrane on the transmitter-output side of a synapse (axon terminal).
Mood disorder characterized by prolonged feelings of worthlessness and guilt, the disruption of normal eating habits, sleep disturbances, a general slowing of behavior, and frequent thoughts of suicide.
gamma-aminobutyric acid (GABA)
Amino acid neurotransmitter that inhibits neurons.
Gap that separates the presynaptic membrane from the postsynaptic membrane.
Neurotransmitter that controls arousal and waking; can cause the constriction of smooth muscles and so, when activated in allergic reactions, contributes to asthma, a constriction of the airways.
carbon monoxide (CO)
Gas that acts as a neurotransmitter in the activation of cellular metabolism.
Relatively permanent change in behavior that results from experience.
Embedded membrane protein, with a binding site for a neurotransmitter but no pore, linked to a G protein that can affect other receptors or act with second messengers to affect other cellular processes.
Protein molecule that pumps substances across a membrane.
Any enzyme that is in limited supply, thus restricting the pace at which a chemical can be synthesized.
Behavioral disorder characterized by delusions, hallucinations, disorganized speech, blunted emotion, agitation or immobility, and a host of associated symptoms.
Disorder of the motor system correlated with a loss of dopamine in the brain and characterized by tremors, muscular rigidity, and reduction in voluntary movement.
Neuron that uses acetylcholine as its main neurotransmitter. The term cholinergic applies to any neuron that uses ACh as its main transmitter.
Guanyl-nucleotide-binding protein coupled to a metabotropic receptor that, when activated, binds to other proteins.
gap junction (electrical synapse)
Fused prejunction and postjunction cell membrane in which connected ion channels form a pore that allows ions to pass directly from one neuron to the next.
Quick-acting neurotransmitter synthesized in the axon terminal from products derived from the diet.
"Self-receptor" in a neural membrane that responds to the transmitter released by the neuron.
Membrane on the transmitter-input side of a synapse (dendritic spine).
Amine neurotransmitter that plays a role in regulating mood and aggression, appetite and arousal, the perception of pain, and respiration.
Chemical released by a neuron onto a target with an excitatory or inhibitory effect.
Learning behavior in which the response to a stimulus strengthens with repeated presentations of that stimulus because the stimulus is novel or because the stimulus is stronger than normal-for example, after habituation has occurred.
Multifunctional chain of amino acids that acts as a neurotransmitter; synthesized from mRNA on instructions from the cell's DNA. Peptide neurotransmitters can act as hormones and may contribute to learning.
Protein that has a binding site for a specific neurotransmitter and is embedded in the membrane of a cell.
Amine neurotransmitter that plays a role in coordinating movement, in attention and learning, and in behaviors that are reinforcing.
Membranous compartment that holds several vesicles containing a neurotransmitter.
posttraumatic stress disorder (PTSD)
Syndrome characterized by physiological arousal symptoms related to recurring memories and dreams related to a traumatic event for months or years after the event.
Disordered mental state of extreme excitement.
Deactivation of a neurotransmitter when membrane transporter proteins bring the transmitter back into the presynaptic axon terminal for subsequent reuse.
norepinephrine (NE, or noradrenaline)
Neurotransmitter found in the brain and in the sympathetic division of the autonomic nervous system; accelerates heart rate in mammals.
Amino acid neurotransmitter that excites neurons.
quantum (pl. quanta)
Amount of neurotransmitter, equivalent to the contents of a single synaptic vesicle, that produces a just observable change in postsynaptic electric potential.
Neural pathways that coordinate brain activity through a single neurotransmitter; cell bodies are located in a nucleus in the brainstem and axons are distributed through a wide region of the brain.
Chemical that carries a message to initiate a biochemical process when activated by a neurotransmitter (the first messenger).
Degenerative brain disorder related to aging that first appears as progressive memory loss and later develops into generalized dementia.
Junction at which messenger molecules are released when stimulated by an action potential.
epinephrine (EP, or adrenaline)
Chemical messenger that acts as a hormone to mobilize the body for fight or flight during times of stress and as a neurotransmitter in the central nervous system.
obsessive-compulsive disorder (OCD)
Behavior disorder characterized by compulsively repeated acts (such as hand washing) and repetitive, often unpleasant, thoughts (obsessions).
From adrenaline, Latin for 'epinephrine'; a neuron containing norepinephrine.