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Tear Duct
The nasolacrimal duct (also called the tear duct) carries tears from the lacrimal sac of the eye into the nasal cavity. The duct begins in the eye socket between the maxillary and lacrimal bones, from where it passes downwards and backwards. The opening of the nasolacrimal duct into the inferior nasal meatus of the nasal cavity is partially covered by a mucosal fold ( valve of Hasner or ''plica lacrimalis''). Excess tears flow through the nasolacrimal duct which drains into the inferior nasal meatus. This is the reason the nose starts to run when a person is crying or has watery eyes from an allergy, and why one can sometimes taste eye drops. This is for the same reason when applying some eye drops it is often advised to close the nasolacrimal duct by pressing it with a finger to prevent the medicine from escaping the eye and having unwanted side effects elsewhere in the body as it will proceed through the canal to the Nasal Cavity. Like the lacrimal sac, the duct is lined by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congenital Lacrimal Duct Obstruction
Nasolacrimal duct obstruction is the obstruction of the nasolacrimal duct and may be either congenital or acquired. Obstruction of the nasolacrimal duct leads to the excess overflow of tears called epiphora. Sign and symptoms Excessive tearing is the most common complaint of patients with nasolacrimal duct obstruction, followed by acute or chronic infections. Pain at the side of the nose suggests dacryocystitis. Nasolacrimal duct obstruction is more common with increasing age and more common in females than males. Cause Involutional stenosis Involutional stenosis is probably the most common cause of nasolacrimal duct obstruction in older people. It affects women twice as frequently as men. Although the inciting event in this process is unknown, clinicopathologic study suggests that compression of the lumen of the nasolacrimal duct is caused by inflammatory infiltrates and edema. This may be the result of an unidentified infection or possibly an autoimmune disease. Da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nasolacrimal Duct Obstruction
Nasolacrimal duct obstruction is the obstruction of the nasolacrimal duct and may be either congenital or acquired. Obstruction of the nasolacrimal duct leads to the excess overflow of tears called epiphora. Sign and symptoms Excessive tearing is the most common complaint of patients with nasolacrimal duct obstruction, followed by acute or chronic infections. Pain at the side of the nose suggests dacryocystitis. Nasolacrimal duct obstruction is more common with increasing age and more common in females than males. Cause Involutional stenosis Involutional stenosis is probably the most common cause of nasolacrimal duct obstruction in older people. It affects women twice as frequently as men. Although the inciting event in this process is unknown, clinicopathologic study suggests that compression of the lumen of the nasolacrimal duct is caused by inflammatory infiltrates and edema. This may be the result of an unidentified infection or possibly an autoimmune disease ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tears
Tears are a clear liquid secreted by the lacrimal glands (tear gland) found in the eyes of all land mammals. Tears are made up of water, electrolytes, proteins, lipids, and mucins that form layers on the surface of eyes. The different types of tears—basal, reflex, and emotional—vary significantly in composition. The functions of tears include lubricating the eyes (basal tears), removing irritants (reflex tears), and also aiding the immune system. Tears also occur as a part of the body's natural pain response. Emotional secretion of tears may serve a biological function by excreting stress-inducing hormones built up through times of emotional distress. Tears have symbolic significance among humans. Physiology Chemical composition Tears are made up of three layers: lipid, aqueous, and mucous. Tears are composed of water, salts, antibodies, and lysozymes (antibacterial enzymes); though composition varies among different tear types. The composition of tears caused by an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goblet Cells
Goblet cells are simple columnar epithelial cells that secrete gel-forming mucins, like mucin 5AC. The goblet cells mainly use the merocrine method of secretion, secreting vesicles into a duct, but may use apocrine methods, budding off their secretions, when under stress. The term '' goblet'' refers to the cell's goblet-like shape. The apical portion is shaped like a cup, as it is distended by abundant mucus laden granules; its basal portion lacks these granules and is shaped like a stem. The goblet cell is highly polarized with the nucleus and other organelles concentrated at the base of the cell and secretory granules containing mucin, at the apical surface. The apical plasma membrane projects short microvilli to give an increased surface area for secretion. Goblet cells are typically found in the respiratory, reproductive and gastrointestinal tracts and are surrounded by other columnar cells. Biased differentiation of airway basal cells in the respiratory epithelium, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Apparatus
The lacrimal apparatus is the physiological system containing the orbital structures for tear production and drainage.Cassin, B. and Solomon, S. ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company, 1990. It consists of: * The lacrimal gland, which secretes the tears, and its excretory ducts, which convey the fluid to the surface of the human eye; it is a j-shaped serous gland located in lacrimal fossa. * The lacrimal canaliculi, the lacrimal sac, and the nasolacrimal duct, by which the fluid is conveyed into the cavity of the nose, emptying anterioinferiorly to the inferior nasal conchae from the nasolacrimal duct; * The innervation of the lacrimal apparatus involves both the a sympathetic supply through the carotid plexus of nerves around the internal carotid artery, and parasympathetically from the lacrimal nucleus of the facial nerve. The blood supply to the lacrimal gland is provided by the ophthalmic artery with its branch - the lacrimal a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fox News
The Fox News Channel, abbreviated FNC, commonly known as Fox News, and stylized in all caps, is an American multinational conservative cable news television channel based in New York City. It is owned by Fox News Media, which itself is owned by the Fox Corporation. The channel broadcasts primarily from studios at 1211 Avenue of the Americas in Midtown Manhattan. Fox News provides service to 86 countries and overseas territories worldwide, with international broadcasts featuring Fox Extra segments during ad breaks. The channel was created by Australian-American media mogul Rupert Murdoch in 1996 to appeal to a conservative audience, hiring former Republican media consultant and CNBC executive Roger Ailes as its founding CEO. It launched on October 7, 1996, to 17 million cable subscribers. Fox News grew during the late 1990s and 2000s to become the dominant United States cable news subscription network. , approximately 87,118,000 U.S. households (90.8% of television subscr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wall Street Journal
''The Wall Street Journal'' is an American business-focused, international daily newspaper based in New York City, with international editions also available in Chinese and Japanese. The ''Journal'', along with its Asian editions, is published six days a week by Dow Jones & Company, a division of News Corp. The newspaper is published in the broadsheet format and online. The ''Journal'' has been printed continuously since its inception on July 8, 1889, by Charles Dow, Edward Jones, and Charles Bergstresser. The ''Journal'' is regarded as a newspaper of record, particularly in terms of business and financial news. The newspaper has won 38 Pulitzer Prizes, the most recent in 2019. ''The Wall Street Journal'' is one of the largest newspapers in the United States by circulation, with a circulation of about 2.834million copies (including nearly 1,829,000 digital sales) compared with ''USA Today''s 1.7million. The ''Journal'' publishes the luxury news and lifestyle magazin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Humans
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, and language. Humans are highly social and tend to live in complex social structures composed of many cooperating and competing groups, from families and kinship networks to political states. Social interactions between humans have established a wide variety of values, social norms, and rituals, which bolster human society. Its intelligence and its desire to understand and influence the environment and to explain and manipulate phenomena have motivated humanity's development of science, philosophy, mythology, religion, and other fields of study. Although some scientists equate the term ''humans'' with all members of the genus ''Homo'', in common usage, it generally refers to ''Homo sapiens'', the only extant member. Anatomically ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dacryocystocele
Dacryocystocele (Dacryocystitis) or timo cyst is a benign, bluish-gray mass in the inferomedial canthus that develops within a few days or weeks after birth. The uncommon condition forms as a result as a consequence of narrowing or obstruction of the nasolacrimal duct, usually during prenatal development. Nasolacrimal duct obstruction disrupts the lacrimal drainage system, eventually creating a swelling cyst in the lacrimal sac area by the nasal cavity. The location of the cyst can cause respiratory dysfunction, compromising the airway. The obstruction ultimately leads to epiphora, an abundance of tear production. Signs and symptoms Dacryocystocele is a condition that can occur to all, at any age. However, the population most affected by this rare condition are infants. The intensity of the symptoms may vary depending on the type of dacryocystocele. There are three types of dacrycystocele: acute, congenital and chronic. Acute dacryocystocele is a bacterial infection, that includes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epiphora (medical)
Epiphora is an overflow of tears onto the face, other than caused by normal crying. It is a clinical sign or condition that constitutes insufficient tear film drainage from the eyes, in that tears will drain down the face rather than through the nasolacrimal system. Cause Causes of epiphora are any that cause either overproduction of tears or decreased drainage of tears, resulting in tearing onto the cheek. This can be due to ocular irritation and inflammation (including trichiasis and entropion) or an obstructed tear outflow tract which is divided according to its anatomical location (i.e. ectropion, punctal, canalicular or nasolacrimal duct obstruction). The latter is often due to aging (a spontaneous process), conjunctivochalasis, infection (i.e. dacryocystitis), rhinitis, and in neonates or infants, failure of the nasolacrimal duct to open. Another cause could be poor reconstruction of the nasolacrimal duct system after trauma to the area. Cause of trauma could be facia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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