All articles starting with H
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Hypoaspis
Hypoaspis is a genus of Laelapidae mites (Mesostigmata) described by Canestrini in 1884, once a broad catch-all genus now restricted to about 36 soil predatory species; its former members include the biocontrol mites Gaeolaelaps aculeifer and Stratiolaelaps scimitus.
Hypobromous acid
Hypobromous acid (HOBr) is a weak bromine oxoacid formed in water when bromide is oxidized, the active biocidal form of bromine disinfectants and a reactive oxidant in the human body.
Hypocalcemia
Hypocalcemia, or low blood calcium, is an abnormally low serum calcium level caused by hypoparathyroidism, vitamin D deficiency, or kidney disease, treatable with calcium and vitamin D.
Hypocalcemic vitamin D-dependent rickets
Hypocalcemic vitamin D-dependent rickets (VDDR type 1, VDDR1A/VDDR1B; 1-alpha-hydroxylase deficiency) is a rare autosomal recessive disorder of vitamin D activation causing infantile hypocalcemia and rickets, treated with calcitriol.
Hypocalcemic vitamin D-resistant rickets
Hypocalcemic vitamin D-resistant rickets (HVDRR, VDDR2A, OMIM 277440) is a rare autosomal recessive rickets caused by VDR gene mutations, causing calcitriol resistance, hypocalcemia, elevated calcitriol, and alopecia in about half to two-thirds of patients.
Hypocalciuria
Hypocalciuria (low urinary calcium; ICD-11 MF98.3), also called low urine calcium. Key causes: familial hypocalciuric hypercalcemia (CASR, GNA11, AP2S1 mutations), thiazides, lithium, vitamin D deficiency; CCCR <0.01 suggests FHH over primary hyperparathyroidism.
Hypocapnia
Hypocapnia, also called hypocarbia, is an arterial CO2 partial pressure below 35 mm Hg (normal 35-45), usually from hyperventilation, causing respiratory alkalosis and cerebral vasoconstriction; transiently lifesaving for intracranial hypertension but harmful when prolonged.
Hypocenter
A hypocenter, also called the focus, is the point within the Earth where an earthquake rupture starts; the epicenter lies directly above, and focal depth strongly affects shaking intensity.
Hypochlorite
Hypochlorite is the oxyanion of chlorine in the +1 oxidation state, OCl⁻, and the family of salts containing it, including sodium hypochlorite, the active ingredient in bleach.
Hypochlorous acid
Hypochlorous acid (HOCl, also written HClO) is a weak acid that exists only in water, formed when chlorine dissolves, and is the active microbicidal form of chlorine in disinfection.
Hypochondriasis
Hypochondriasis: persistent preoccupation with having serious illness despite reassurance; DSM-IV somatoform diagnosis, split by DSM-5 into illness anxiety disorder and somatic symptom disorder, retained in ICD-11.
Hypochondroplasia
Hypochondroplasia is an uncommon hereditary disorder of skeletal development caused by mutations in the FGFR3 gene, producing short stature with disproportionately short limbs, typically milder than achondroplasia.
Hypochromic anemia
Hypochromic anemia (historically chlorosis): anemia with abnormally low red cell hemoglobin concentration (MCHC < 32 g/dL), usually microcytic; most often iron deficiency, but thalassemia, sideroblastic anemia, and lead poisoning must be distinguished by iron studies.
Hypocomplementemic urticarial vasculitis
Hypocomplementemic urticarial vasculitis (HUV, McDuffie syndrome, HUVS) is a rare anti-C1q immune complex small vessel vasculitis with chronic urticaria, low C1q/C3/C4, arthritis, ocular, renal, and pulmonary involvement.
Hypocrea
Hypocrea Fr. (1825), type genus of Hypocreaceae, is the sexual teleomorph genus of Trichoderma molds, typified by H. rufa; since the 2011 one-fungus-one-name rules Trichoderma (1794) is the accepted name.
Hypocreales
Hypocreales (Lindau, 1897) is an order of Sordariomycetes fungi in Ascomycota, parasitic on plants, insects, or fungi, or saprotrophic; includes Beauveria, Cordyceps, Fusarium, and Trichoderma, spanning plant pathogens, biocontrol agents, antibiotics, and mycotoxins.
Hypocrisy
Hypocrisy (Greek hupokrasis, acting a part) is claiming moral standards one's conduct does not meet; covers pretence and double-standard traditions, Batson's moral hypocrisy experiments, the hypocrisy-either-way effect, cultural variation, and debates over its wrongness.
Hypocrisy (group)
Hypocrisy is a Swedish death metal band from Ludvika, formed around 1990 by guitarist and vocalist Peter Tägtgren, known for Roswell 47 and thirteen albums through Worship (2021).
Hypocycloid gear
A hypocycloid gear is a gear profile in which a gear rolls inside a fixed ring gear, used in compact speed reducers with large reduction ratios.
Hypodermic needle
Hypodermic needle: hollow stainless steel tube on a Luer hub for injecting medication or aspirating fluid below the skin; FDA Class II (880.5570), ISO 7864 single-use standard, sizes 0.18-3.4 mm, invented from Rynd's 1844 needle and Wood/Pravaz 1853 syringes.
Hypodermoclysis
Hypodermoclysis, or subcutaneous fluid infusion, rehydrates mildly to moderately dehydrated patients, especially older adults and palliative care patients, when venous access is difficult; about 3 L daily at two sites.
Hypodontia
Hypodontia, also called tooth agenesis or partial anodontia, is the developmental absence of one or more teeth, affecting 2–8% of people for permanent teeth; linked to PAX9, MSX1, AXIN2, EDA, and WNT10A mutations and treated by orthodontics, bridges, or implants.
Hypodontia-dysplasia of nails syndrome
Hypodontia-dysplasia of nails syndrome, also known as Witkop syndrome or tooth and nail syndrome, is a rare autosomal dominant ectodermal dysplasia causing missing permanent teeth and dysplastic nails, first described in 1965.
Hypogastric plexus
The hypogastric plexus is a network of nerve fibers in the pelvis, divided into superior and inferior parts, that supplies autonomic innervation to the bladder, rectum, and reproductive organs.
Hypogeum of Clepsina
Hypogeum of Clepsina (Ipogeo di Clepsina), a painted subterranean sanctuary at Caere (Cerveteri), named for prefect Gaius Genucius Clepsina; frescoes dated about 273 BC, solstice-aligned niche, Rosalia festival use.
Hypogeum of the Aurelii
Hypogeum of the Aurelii (Ipogeo degli Aureli), an early 3rd-century AD private freedman tomb on Rome's ancient Via Labicana near Porta Maggiore, discovered in 1919, with debated frescoes and a mosaic inscription of Aurelius Felicissimus.
Hypogeum of via Dino Compagni
Hypogeum of via Dino Compagni (Ipogeo di via Dino Compagni), also the Via Latina Catacomb: a fourth-century private Roman burial hypogeum with over 100 Christian and pagan frescoes, found in 1955, closed to the public.
Hypoglossal nerve
Hypoglossal nerve (cranial nerve XII): pure motor nerve from the medulla's hypoglossal nucleus, exiting via the hypoglossal canal, supplying all tongue muscles except palatoglossus; lesions deviate the tongue toward the lesion.
Hypoglossal nerve stimulation
Hypoglossal nerve stimulation is a surgically implanted therapy that moves the tongue forward during sleep to treat obstructive sleep apnea in adults who cannot use CPAP.
Hypoglossia-hypodactyly syndrome
Hypoglossia-hypodactyly syndrome, also called Hanhart syndrome or aglossia-adactylia, is a rare congenital condition combining an underdeveloped tongue, a small lower jaw, and limb defects ranging from missing finger and toe bones to absent digits or limbs.