Copy of `Dorland's Medical Dictionary`

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Dorland's Medical Dictionary Category: Health and Medicine > Medical Dictionary Date & country: 31/12/2010, USA Words: 39128

hilar cell tumor
a rare benign neoplasm of the hilum of the ovary, histologically resembling a Leydig cell tumor of the testis.

hilar tuberculosis
pulmonary tuberculosis involving the hilum of a lung.

Hill sign
disproportionate femoral systolic hypertension, seen in aortic regurgitation and certain other conditions involving increased stroke volume.

hillock
(hil´әk) a small prominence or elevation.

hilum
(hi´lәm) pl. hi´la a depression or pit at the part of an organ where vessels and nerves enter.

hilum cells
groups of large epithelioid cells closely associated with vascular spaces and unmyelinated nerve fibers in the hilum of the ovary and the adjacent mesovarium.

hilus
(hi´lәs) pl. hi´li hilum.

hindbrain
(hīnd´brān″) rhombencephalon.

hindfoot
(hīnd´foot″) the posterior portion of the foot, comprising the region of the talus and calcaneus.

hindgut
(hīnd´gut″) a pocket formed beneath the caudal portion of the developing embryo, which develops into the distal portion of the small intestine, colon, and rectum.

Hines and Brown test
cold pressor test.

Hines-Bannick syndrome
(hīnz´ ban´ik) intermittent attacks of low temperature and disabling sweating.

hinge joint
a synovial joint that allows movement in only one plane, forward and backward. Examples are the elbow and the interphalangeal joints of the fingers. The jaw is primarily a hinge joint but it can also move somewhat from side to side. The knee and ankle joints are hinge joints that also allow some rotary movement. Called also ginglymus...

hinge position
the position of the condyle in the temporomandibular joint from which an opening by hinge movement is possible beyond the amplitude of rest position.

hinge-axis point
a reference point on the skin corresponding with the terminal hinge axis of the mandible.

Hinman syndrome
(hin´mәn) a psychogenic disorder seen in children, imitating a neurogenic bladder, consisting of detrusor-sphincter dyssynergia without evidence of any neural lesions. Called also nonneurogenic neurogenic bladder.

hip
(hip) the area around the hip joint (the articulation of the femur and the acetabulum) at the base of the lower abdomen. Called also coxa.

hip bone
the large bone in the hip, consisting of the ilium, ischium, and pubic bone.

hip flexion phenomenon
in paraplegia, when the patient attempts to rise from a lying position, the hip flexes on the paralyzed side.

hip joint
the synovial joint in the lower abdomen where the head of the femur fits into the acetabulum.

hip joint disease
tuberculosis of the hip joint; called also coxalgia.

Hippel disease
see von Hippel disease.

Hippel-Lindau disease
see .

hippocampal fissure
one extending from the splenium of the corpus callosum almost to the tip of the temporal lobe; called also hippocampal sulcus.

hippocampal gyrus
one on the inferior surface of each cerebral hemisphere, lying between the hippocampal and collateral fissures; called also parahippocampal gyrus.

hippocampal sclerosis
loss of neurons in the region of the hippocampus, with gliosis; sometimes seen in epilepsy.

hippocampal sulcus
hippocampal fissure.

hippocampus
(hip″o-kam´pәs) a curved elevation of gray matter on the floor of the inferior horn of the lateral ventricle; it is an important functional component of the limbic system.

hippocratic
(hip″o-krat´ik) relating to Hippocrates.

hippocratic facies
a drawn, pinched, and livid appearance indicative of approaching death.

Hippocratic Oath
a moral code for ethical conduct and practice in medicine, established according to the ideals of Hippocrates. The text is as follows: “I swear by Apollo the physician, by Aesculapius, Hygeia, and Panacea, and I take to witness all the gods, all the goddesses, to keep according to my ability and my judgment the following ...

hippuric acid
(hĭ-pūr´ik) a compound formed by conjugation of benzoic acid and glycine; it occurs in the urine of herbivorous animals, rarely in human urine.

hippus
(hip´әs) abnormal exaggeration of the rhythmic contraction and dilation of the pupil, independent of changes in illumination or in fixation of the eyes.

Hirano bodies
glassy, eosinophilic, rod-shaped inclusions, composed primarily of actin, seen in the cytoplasm of neurons of the central nervous system, chiefly the hippocampus, particularly in older persons; although they may occur in the absence of disease, they are more prevalent in patients with neurodegenerative disorders such as A...

hirci
(hur´si) sing. hir´cus the hairs growing in the armpit.

Hirschberg reflex
Hirschberg sign adduction, inversion, and slight plantar flexion of the foot on stroking the inner aspect (not the sole) of the foot from the great toe to the heel; called also adductor reflex of foot.

Hirschsprung disease
(hirsh´sproong) congenital absence of parasympathetic nerve ganglia in part or all of the colon, resulting in absence of peristalsis in that portion and massive enlargement of the part preceding it, with constipation and obstruction. Called also aganglionic or congenital megacolon.

hirsute
(hur´soot) having abundant or excessive hair; see also hirsutism.

hirsuties
(hir-soo´she-ēz) hirsutism.

hirsutism
(hur´soot-iz-әm) abnormal hairiness, especially in women.

hirudicide
(hĭ-roo´dĭ-sīd) an agent destructive to leeches.

hirudin
(hĭ-roo´din) the active principle of the buccal secretion of leeches; it prevents clotting of the blood. A product made with recombinant technology is used as an anticoagulant.

His disease
(his) trench fever.

His zones
four thickenings running the entire length of the embryonic spinal cord.

His-Purkinje system
the intraventricular conduction system from the bundle of His to the distal Purkinje fibers, which carries the impulse to the ventricles.

His-ventricular (H-V) interval
an interval of the electrogram of the bundle of His, measured from the earliest onset of the His potential to the onset of ventricular activation as recorded on eight of the intracardiac bipolar His bundle leads or any of the multiple surface ECG leads; it reflects conduction time through the His-Purkinje system.

His-Werner disease
(his´ ver´ner) trench fever.

histaminase
(his-tam´ĭ-nās) an enzyme that inactivates histamine.

histamine
(his´tә-mēn) an amine, C5H9N3 found in all body tissues, produced by decarboxylation of histidine. It induces numerous physiological changes in the body: capillary dilation, which increases capillary permeability and lowers blood pressure; contraction of most smooth muscle tissue; increased secretion of gastr...

histamine flare test
(for leprosy and postherpetic neuralgia) a drop of 1:1000 histamine acid phosphate solution is placed on the skin and a needle puncture is made through it; the test is positive if there is no erythema flare when the puncture is made within the suspected lesion area, or if the flare stops at the border of the lesion when i...

histamine headache
cluster headache.

histamine receptors
receptors for histamine. H1-receptors mediate contraction of smooth muscles and dilation of capillaries, causing effects such as bronchoconstriction and contraction of the intestine; they are blocked by antihistamines such as pyrilamine or chlorpheniramine. H2-receptors mediate acceleration of the heart rate and cause gastric acid se...

histamine test
any of several formerly common gastric function tests in which histamine was injected to stimulate secretion and measure output of hydrochloric acid by the stomach. a formerly used test for presence of a pheochromocytoma; persons with such a tumor would show first a fall and then a marked rise in blood pressure.&...

histamine-releasing factor
(HRF) a lymphokine, believed to be produced by macrophages and B lymphocytes, that induces the release of histamine by basophils bound to the IgE class of immunoglobulin. It occurs in sensitive individuals in late phase allergic reactions six or more hours after contact with the antigen.

histaminemia
(his-tam″ĭ-ne´me-ә) histamine in the blood.

histaminergic
(his″tә-min-ur´jik) pertaining to the effects of histamine at histamine receptors of target tissues, which are blocked by antihistamines.

histidase
(his´tĭ-dās) an enzyme of the liver that converts histidine to urocanic acid.

histidine
(his´tĭ-dēn) a naturally occurring essential amino acid that is necessary for optimal growth of infants; its decarboxylation results in formation of histamine.

histidine loading test
(for folic acid deficiency) a loading dose of histidine is given, and the resultant urinary excretion of excess formiminoglutamic acid (FIGLU), secondary to decreased amounts of tetrahydrofolic acid, is measured. Called also FIGLU excretion test.

histidinemia
(his″tĭ-dĭ-ne´me-ә) a hereditary aminoacidopathy marked by excessive histidine in the blood and urine due to deficient histidase activity; many affected persons show mild mental retardation and disordered speech development.

histidinuria
(his″tĭ-dĭ-nu´re-ә) an aminoaciduria consisting of excessive histidine in the urine, usually in either histidinemia or during pregnancy.

histiocyte
(his´te-o-sīt″) macrophage. adj., histiocyt´ic., adj.

histiocytic leukemia
acute monocytic leukemia.

histiocytic lymphoma
a rare type of non-Hodgkin lymphoma of intermediate to high malignancy, characterized by large tumor cells that resemble histiocytes but are considered to be of lymphoid origin. Many tumors formerly placed in this category are now considered to belong in one of the large cell lymphoma groups.

histiocytoma
(his″te-o-si-to´mә) a tumor containing histiocytes (macrophages). benign fibrous histiocytoma any of a group of benign neoplasms in the dermis containing histiocytes and fibroblasts; the term sometimes encompasses types such as dermatofibroma, nodular subepidermal fib...

histiocytosis
(his″te-o-si-to´sis) the abnormal appearance of histiocytes in the blood. Langerhans cell histiocytosis any of several disorders characterized by proliferation of Langerhans cells (specialized cells found in the skin that are part of the immune system); all are believed to arise fro...

histiogenic
(his″te-o-jen´ik) formed by the tissues.

histioid
(his´te-oid) histoid.

histioid tumor
one formed of a single tissue resembling that of the surrounding parts.

histoblast
(his´to-blast) a tissue-forming cell.

histochemistry
(his″to-kem´is-tre) that branch of histology that deals with the identification of chemical components in cells and tissues.

histoclinical
(his″to-klin´ĭ-kәl) combining histological and clinical evaluation.

histocompatibility
(his″to-kәm-pat″ĭ-bil´ĭ-te) the quality of a cellular or tissue graft enabling it to be accepted and functional when transplanted to another organism. the degree to which two individuals are histocompatible. adj., histocompat´ible., adj.

histocompatibility antigens
genetically determined isoantigens present on the cell membranes of nucleated cells of most tissues, which incite an immune response when grafted onto a genetically disparate individual and thus determine the compatibility of tissues in transplantation. Major histocompatibility antigens are those that belong to the major ...

histocompatibility gene
one that determines the specificity of tissue antigenicity (HLA antigens) and thus the compatibility of donor and recipient in tissue transplantation and blood transfusion.

histodialysis
(his″to-di-al´ә-sis) disintegration or breaking down of tissue.

histodifferentiation
(his″to-dif″әr-en″she-a´shәn) the acquisition of tissue characteristics by cell groups during development.

histogenesis
(his″to-jen´ә-sis) differentiation of cells into the specialized tissues forming the various organs and parts of the body.

histogram
(his´to-gram) a graph in which values found in a quantitative study are represented by lines or symbols placed horizontally or vertically, to indicate frequency distribution.

histoid
(his´toid) developed from one kind of tissue. resembling one of the tissues of the body.

histoincompatibility
(his″to-in″kәm-pat″ĭ-bil´ĭ-te) the quality of a cellular or tissue graft preventing its acceptance or functioning when transplanted to another organism; said of the relationship between the genotypes (histocompatibility genes) of donor and host in which a graft generally will be r...

histokinesis
(his″to-kĭ-ne´sis) movement in the tissues of the body.

histologic accommodation
changes in morphology and function of cells following changed conditions.

histologist
(his-tol´ә-jist) a specialist in histology.

histology
(his-tol´ә-je) that department of anatomy dealing with the minute structure, composition, and function of tissues. adj., histolog´ic, histolog´ical., adj. pathologic histology the science of diseased tissues.

histolysis
(his-tol´ә-sis) breaking down of tissues. adj., histolyt´ic., adj.

histone
(his´tōn) a simple protein, soluble in water and insoluble in dilute ammonia, found combined as salts with acidic substances, such as nucleic acids or the globin of hemoglobin.

histopathology
(his″to-pә-thol´ә-je) pathologic histology.

histophysiology
(his″to-fiz″e-ol´ә-je) the correlation of function with the microscopic structures of cells and tissues.

Histoplasma
(his″to-plaz´mә) a genus of fungi. H. capsula´tum causes histoplasmosis in humans.

histoplasmin
(his″to-plaz´min) a skin test antigen prepared from the fungus Histoplasma capsulatum. Because positive skin tests are common in endemic areas and indicate only previous exposure, not necessarily active disease, histoplasmin is not useful in diagnosis of histoplasmosis. It is used primarily in epidemiologic survey...

histoplasmoma
(his″to-plaz-mo´mә) a rounded granuloma of the lung due to infection with Histoplasma capsulatum; seen radiographically as a coin-shaped lesion.

histoplasmosis
(his″to-plaz-mo´sis) a systemic fungal disease that is caused only by the breathing in of dust contaminated by Histoplasma capsulatum and is not contagious. It is common in rural areas of the midwestern United States and is found in many other parts of the world. The infection begins in the lungs and may spread to...

historrhexis
(his″to-rek´sis) the breaking up of tissue.

history
(his´tә-re) a systematic account of events. case history the collected data concerning an individual, the family, and environment; it includes the medical history and any other information that may be useful in analyzing and diagnosing the case or for instructional or research purpo...

histothrombin
(his″to-throm´bin) thrombin derived from connective tissue.

histotome
(his´to-tōm) a cutting instrument used in microtomy; microtome.

histotomy
(his-tot´ә-me) dissection of tissues; microtomy.

histotoxic
(his´to-tok″sik) poisonous to tissue.

histotoxic hypoxia
that caused by decreased uptake of oxygen by tissues, as in cyanide poisoning.