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serotonin

n. a common monoamine neurotransmitter in the brain, particularly the raphe nucleus, and in other parts of the central nervous system; it also is found in the gastrointestinal tract, in smooth muscles of the cardiovascular and bronchial systems, and in blood platelets. It is synthesized from the dietary amino acid L-tryptophan (see tryptophan hydroxylase), and in the pineal gland it is converted to melatonin. It is primarily degraded by monoamine oxidase, which yields its principal metabolic product, 5-hydroxyindoleacetic acid (5-HIAA). Serotonin has roles in emotional processing, mood, appetite, sexual desire and performance, sleep, pain processing, hallucinations, and reflex regulation. For example, levels of serotonin correlate negatively with aggression, and release of serotonin may promote sleep. It is implicated in many psychological conditions, including depressive disorders, anxiety disorders, sleep disorders, aggression, and psychosis; many common psychotropic drugs affect neurotransmission mediated by serotonin. Also called 5-hydroxytryptamine (5-HT).

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Psychology term of the day

April 26th 2024

general paresis

general paresis

dementia associated with advanced neurosyphilitic infection of the brain (see neurosyphilis), a condition that is now extremely rare because syphilis is usually diagnosed and treated in its early stages. The first symptoms of general paresis appear 5 to 30 years after the primary infection. Psychological signs are irritability, confusion, fatigue, and forgetfulness, followed by headaches, confabulation, and deterioration in behavior and judgment. If untreated with antibiotics, physical signs gradually develop, including Argyll Robertson pupils, sagging facial muscles, vacant expression, slurred speech, poor handwriting, and locomotor ataxia, followed by inability to dress, paralysis, convulsions, loss of bladder and bowel control, and gradual deterioration to a vegetative state. General paresis was formerly known as general paralysis of the insane, dementia paralytica, paralytic dementia, and paretic psychosis. Also called general paralysis.