Somnolence (alternatively sleepiness or drowsiness ) is a state of strong desire for sleep , or sleeping for unusually long periods (compare hypersomnia ). It has distinct meanings and causes. It can refer to the usual state preceding falling asleep , the condition of being in a drowsy state due to circadian rhythm disorders, or a symptom of other health problems. It can be accompanied by lethargy , weakness and lack of mental agility.
19-487: PVA may refer to: Science and technology [ edit ] Paraventricular nucleus of hypothalamus , a part of the brain Patterned vertical alignment , a thin-film-transistor liquid-crystal display technology Poikiloderma vasculare atrophicans , a skin disease Polyvinyl acetate , an adhesive used for porous materials like wood, paper, and cloth Polyvinyl alcohol ,
38-418: A disorder. Sleepiness can be dangerous when performing tasks that require constant concentration, such as driving a vehicle. When a person is sufficiently fatigued , microsleeps may be experienced. In individuals deprived of sleep, somnolence may spontaneously dissipate for short periods of time; this phenomenon is the second wind , and results from the normal cycling of the circadian rhythm interfering with
57-421: A response to infection. Such somnolence is one of several sickness behaviors or reactions to infection that some theorize evolved to promote recovery by conserving energy while the body fights the infection using fever and other means. Other causes include: Quantifying sleepiness requires a careful assessment. The diagnosis depends on two factors, namely chronicity and reversibility. Chronicity signifies that
76-663: A water-soluble synthetic polymer Population viability analysis , a risk-assessment method used in conservation biology Positive vorticity advection in meteorology Potato virus A , an agricultural disease Other uses [ edit ] Paralyzed Veterans of America , a veterans' service organization Kinder High School for the Performing and Visual Arts , in Houston, Texas, U.S. Perkiomen Valley Academy , in Pennsylvania, U.S. People's Volunteer Army ,
95-408: Is a nucleus in the hypothalamus , that lies next to the third ventricle . Many of its neurons project to the posterior pituitary where they secrete oxytocin , and a smaller amount of vasopressin . Other secretions are corticotropin-releasing hormone (CRH) and thyrotropin-releasing hormone (TRH). CRH and TRH are secreted into the hypophyseal portal system , and target different neurons in
114-593: Is accounting for only about 1% of the brain volume.In the rat, the PVN consists of approximately 100,000 neurons located in a volume of about 0.5 cubic millimetre. The PVN contains magnocellular neurosecretory cells whose axons extend into the posterior pituitary , parvocellular neurosecretory cells that project to the median eminence , ultimately signalling to the anterior pituitary , and several populations of other cells that project to many different brain regions including parvocellular preautonomic cells that project to
133-511: Is crucial to aim for objective measures to quantify the sleepiness. A good measurement tool is the multiple sleep latency test (MSLT). It assesses the sleep onset latency during the course of one day—often from 8:00 to 16:00. An average sleep onset latency of less than 5 minutes is an indication of pathological sleepiness. A number of diagnostic tests, including the Epworth Sleepiness Scale , are available to help ascertain
152-435: The anterior pituitary . Dysfunctions of the PVN can cause hypersomnia in mice. In humans, the dysfunction of the PVN and the other nuclei around it can lead to drowsiness for up to 20 hours per day. The PVN is thought to mediate many diverse functions through different hormones , including osmoregulation , appetite , wakefulness , and the response of the body to stress . The paraventricular nucleus lies adjacent to
171-409: The brainstem and spinal cord . The magnocellular cells in the PVN elaborate and secrete two peptide hormones : oxytocin and vasopressin . These hormones are packaged into large vesicles, which are then transported down the unmyelinated axons of the cells and released from neurosecretory nerve terminals residing in the posterior pituitary gland. Similar magnocellular neurons are found in
190-799: The supraoptic nucleus which also secrete vasopressin and a smaller amount of oxytocin. The axons of the parvocellular neurosecretory neurons of the PVN project to the median eminence, a neurohemal organ at the base of the brain, where their neurosecretory nerve terminals release their hormones at the primary capillary plexus of the hypophyseal portal system . The median eminence contains fiber terminals from many hypothalamic neuroendocrine neurons, secreting different neurotransmitters or neuropeptides, including vasopressin, corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH), gonadotropin-releasing hormone (GnRH), growth hormone-releasing hormone (GHRH), dopamine (DA) and somatostatin (growth hormone release inhibiting hormone, GIH) into blood vessels in
209-421: The third ventricle . It lies within the periventricular zone and is not to be confused with the periventricular nucleus , which occupies a more medial position, beneath the third ventricle . The PVN is highly vascularised and is protected by the blood–brain barrier , although its neuroendocrine cells extend to sites (in the median eminence and in the posterior pituitary ) beyond the blood–brain barrier. PVN
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#1732772597591228-641: The Chinese armed forces active during the Korean War El Embrujo Airport , in Providencia Island, Colombia, IATA code PVA PVA (band) , English music band See also [ edit ] All pages with titles containing PVA Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title PVA . If an internal link led you here, you may wish to change
247-606: The PVN. Inputs from suprachiasmatic nucleus about levels of lighting (circadian rhythms). Inputs from glucose sensors within the brain stimulate release of vasopressin and corticotropin-releasing hormone from parvocellular neurosecretory cells . Somnolence Somnolence is often viewed as a symptom rather than a disorder by itself. However, the concept of somnolence recurring at certain times for certain reasons constitutes various disorders, such as excessive daytime sleepiness , shift work sleep disorder , and others; and there are medical codes for somnolence as viewed as
266-415: The body, by hormonal control. Among these, inputs from neurons in structures adjacent to the anterior wall of the third ventricle (the "AV3V region") carry information about the electrolyte composition of the blood, and about circulating concentrations of such hormones as angiotensin and relaxin , to regulate the magnocellular neurons. Inputs from the brainstem (the nucleus of the solitary tract ) and
285-515: The hypophyseal portal system. The blood vessels carry the peptides to the anterior pituitary gland, where they regulate the secretion of hormones into the systemic circulation. The parvocellular neurosecretory cells include those that make: As well as neuroendocrine neurons, the PVN contains interneurons and populations of neurons that project centrally (i.e., to other brain regions). The centrally-projecting neurons include The PVN receives afferent inputs from many brain regions and different parts of
304-454: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=PVA&oldid=1167042896 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Paraventricular nucleus of hypothalamus The paraventricular nucleus of hypothalamus ( PVN , PVA , or PVH)
323-409: The patient, unlike healthy people, experiences persistent sleepiness which does not pass. Reversibility stands for the fact that, even if the individual goes to sleep, the sleepiness may not be completely gone after waking up. The problem with the assessment is that patients may only report the consequences of sleepiness: loss of energy, fatigue, weariness, difficulty remembering or concentrating, etc. It
342-615: The processes the body carries out to prepare itself to rest. The word "somnolence" is derived from the Latin "somnus" meaning "sleep". Circadian rhythm ("biological clock") disorders are a common cause of drowsiness as are a number of other conditions such as sleep apnea, insomnia and narcolepsy. The body clock disorders are classified as extrinsic (externally caused) or intrinsic. The former type is, for example, shift work sleep disorder, which affects people who work nights or rotating shifts. The intrinsic types include: Sleepiness can also be
361-521: The ventrolateral medulla carry information from the heart and stomach . Inputs from the hippocampus to the CRH neurones are important regulators of stress responses. Inputs from neuropeptide Y -containing neurons in the arcuate nucleus coordinate metabolic regulation (via TRH secretion) with regulation of energy intake. Specifically, the projections from the arcuate nucleus seem to exert their effect on appetite via MC4R -expressing oxytocinergic cells of
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