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Search Beginning of word Full word and in description

3435 entries in this dictionary.
Latest Entries

hirschsprung disease Congenital megacolon resulting from the absence of ganglion cells (aganglionosis) in a distal segment of the large intestine. The aganglionic segment is permanently contracted thus causing dilatation proximal to it. In most cases, the aganglionic segment is within the rectum and sigmoid colon.Treatment is surgical removal of the affected sections, with the remaining colon being joined to the anus. [ Articles | Books | Images | Discussion groups ]

hippus Hippus is a tremor of the iris which produces alternating contraction and dilatation of the pupil. [ Articles | Books | Images | Discussion groups ]

hindbrain The posterior of the three primitive cerebral vesicles of an embryonic brain. It consists of myelencephalon, metencephalon, and isthmus rhombencephali from which develop the major brain stem components, such as medulla oblongata from the myelencephalon, cerebellum and pons from the metencephalon, with the expanded cavity forming the fourth ventricle. [ Articles | Books | Images | Discussion groups ]

herpangina A short febrile illness in which minute vesicles or punched out ulcers develop in the posterior parts of the mouth.Caused by Coxsackie A virus. [ Articles | Books | Images | Discussion groups ]

heroin A narcotic analgesic that may be habit-forming. It is a controlled substance (opium derivative) listed in the U.S. Code of Federal Regulations, Title 21 Parts 329.1, 1308.11 (1987). Sale is forbidden in the United States by Federal statute. (Merck Index, 11th ed) It is powerful analgesic and cough suppresant, but its capacity to produce euphoria rapidly induces dependence. Withdrawal symptoms include restlessness, insomnia, muscle cramps, vomiting and diarrhoea; signs include dilated pupils, raised pulse rate, and disturbed temperature control. [ Articles | Books | Images | Discussion groups ]

clitoris A small,sensitive organ comprising erectile tissue at the top of the female genitalia where the labial folds meet below the pubic bone.Clitorial tissue extends into the anterior roof of the vagina.During sexual excitement the clitoris enlarges and hardens and may be the focus of orgasm. [ Articles | Books | Images | Discussion groups ]

claustrofobia Morbid fear of being in confined space,or the fear experienced while in it.Claustrofobia may develop because of a previous unpleasant experience in a confined space.Cognitive behavior therapy may help patients whose daily lives are affected by this disorder. [ Articles | Books | Images | Discussion groups ]

circumcision A surgical procedure to remove the prepuce of the penis in males and a part or all of the external genitalia in females.It is mainly done for religious or ethnic reasons; there is no medical or surgical reason for procedure.Circumcision in females is damaging procedure, involving the removal of all or parts of clitoris, labia majora or labia minora, sometimes involving narrowing of entrance to the vagina.Total removal of external genitalia is called infibulation. [ Articles | Books | Images | Discussion groups ]

circle of willis A polygonal anastomosis at the base of the brain formed by the internal carotid, proximal parts of the anterior, middle, and posterior cerebral arteries, the anterior communicating artery and the posterior communicating arteries.Congenital defects may occur in these arteries and lead to the formation of aneurysm. [ Articles | Books | Images | Discussion groups ]

ciliary body A ring of tissue extending from the scleral spur to the ora serrata of the retina. It consists of the uveal portion and the epithelial portion. The ciliary muscle is in the uveal portion and the ciliary processes are in the epithelial portion. [ Articles | Books | Images | Discussion groups ]