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

photodamage
(fo´to-dam″әj) damage to the skin from prolonged exposure to ultraviolet radiation; see also actinic dermatitis and photoaging.

photodermatitis
(fo″to-dur″mә-ti´tis) dermatitis caused by exposure to ultraviolet radiation, such as that in sunlight, such as photocontact dermatitis or phototoxic dermatitis.

photodermatosis
(fo″to-dur″mә-to´sis) photodermatitis. any abnormal skin condition caused by a reaction to ultraviolet radiation; cf. photodamage.

photodisruption
(fo″to-dis-rup´shәn) disruption of tissues by laser-produced rapid ionization of molecules.

photodynamic therapy
intravenous administration of hematoporphyrin derivative, which concentrates selectively in metabolically active tumor tissue, followed by exposure of the tumor tissue to red laser light to produce cytotoxic free radicals that destroy hematoporphyrin-containing tissue.

photodynia
(fo″to-din´e-ә) photalgia.

photoelectric effect
ejection of electrons from matter as a result of interaction with photons from high frequency electromagnetic radiation, such as x-rays; the ejected electrons may be energetic enough to ionize multiple additional atoms.

photofluorography
(fo″to-floor-og´rә-fe) the photographic recording of fluoroscopic images on small films, using a fast lens; used in mass radiography of the chest. Called also fluorography and fluororadiography.

photogenic
(fo″to-jen´ik) produced by light. phosphorescent.

photogenic epilepsy
reflex epilepsy brought on by flickering light.

photokinetic
(fo″to-kĭ-net´ik) moving in response to the stimulus of light.

photolysis
(fo-tol´ĭ-sis) chemical decomposition or cleavage of a bond by the action of light or other radiant energy. adj., photolyt´ic., adj.

photolyte
(fo´to-līt) a substance decomposed by light.

photomechanical ablation
laser ablation of tissue in which the absorption of light energy causes stress in excess of the tissue's strength.

photomedicine
(fo″to-med´ĭ-sin) the medical specialty dealing with interactions between light and living systems, such as therapeutic uses such as phototherapy and pathologic effects such as photodermatoses.

photometer
(fo-tom´ә-tәr) a device for measuring the intensity of infrared, ultraviolet, or visible light. a device for testing the sensitivity of the eye to light by determining the light minimum.

photometry
(fo-tom´ә-tre) measurement of the intensity of light.

photomicrograph
(fo″to-mi´kro-graf) a photograph of an object as seen through an ordinary light microscope.

photomyoclonic
(fo″to-mi″o-klon´ik) photomyogenic.

photomyogenic
(fo″to-mi″o-jen´ik) photomyoclonic; denoting an electroencephalographic response to photic stimulation (brief flashes of light) marked by myoclonus of the facial muscles.

photon
(fo´ton) a discrete particle (quantum) of radiant energy.

photoparoxysmal
(fo″to-par″ok-siz´mәl) photoconvulsive; denoting an abnormal electroencephalographic response to photic stimulation (brief flashes of light), marked by diffuse paroxysmal discharge recorded as spike-wave complexes; the response may be accompanied by minor seizures.

photopatch test
a type of patch test for assessing the photosensitization potential of medications and other chemicals. On the patient's back, each substance is applied in two different locations; then one spot of each substance is irradiated. A positive reaction at only the irradiated site of a substance indicates photoallergy; reaction at bo...

photoperceptive
(fo″to-pәr-sep´tiv) able to perceive light.

photoperiod
(fo´to-pēr″e-әd) the period of time per day that an organism is exposed to daylight (or to artificial light). adj., photoperiod´ic., adj.

photoperiodism
(fo″to-pēr´e-әd-iz-әm) the physiologic and behavioral reactions brought about in organisms by changes in the duration of daylight and darkness.

photopheresis
(fo″to-fә-re´sis) a technique for treating cutaneous T-cell lymphoma, in which a photoactive chemical is administered, and the blood is removed and circulated through a source of ultraviolet radiation, then returned to the patient; it is believed to stimulate the immune system.

photophilic
(fo″to-fil´ik) thriving in light.

photophobia
(fo″to-fo´be-ә) abnormal visual intolerance to light. adj., photopho´bic., adj.

photophthalmia
(fo″tof-thal´me-ә) ophthalmia caused by intense light or glare.

photopia
(fo-to´pe-ә) day vision. adj., photop´ic., adj.

photopsia
(fo-top´se-ә) an appearance as of sparks or flashes, in retinal irritation.

photoptarmosis
(fo″to-tahr-mo´sis) sneezing caused by the influence of light.

photoptometer
(fo″top-tom´ә-tәr) an instrument for measuring visual acuity by determining the smallest amount of light that will render an object just visible.

photoreactivation
(fo″to-re-ak″tĭ-va´shәn) reversal of the biological effects of ultraviolet radiation on cells by subsequent exposure to visible light.

photoreceptive
(fo″to-re-sep´tiv) sensitive to stimulation by light.

photoreceptor
(fo″to-re-sep´tәr) a nerve end-organ or receptor sensitive to light; see rod (def. 2) and cone (def. 2).

photoreceptor cells
visual cells.

photorefractive
(fo″to-re-frak´tiv) pertaining to the refraction of light; see photorefractive keratectomy.

photoretinitis
(fo″to-ret″ĭ-ni´tis) retinitis due to exposure to intense light.

photosensitivity
(fo″to-sen″sĭ-tiv´ĭ-te) sensitivity of a cell to light. abnormally heightened sensitivity to sunlight, such as of the eyes or skin; two specific types are photoallergy and phototoxicity. See also photosensitization. adj., photosen´sitive., adj.

photosensitivity dermatitis
any dermatitis occurring as a manifestation of photosensitivity, such as chronic actinic dermatitis, photoallergic contact dermatitis, and phototoxic dermatitis.

photosensitization
(fo″to-sen″sĭ-tĭ-za´shәn) the development of abnormally heightened photosensitivity of the skin or eyes to sunlight.

photostable
(fo´to-sta″bәl) unchanged by the influence of light.

photosynthesis
(fo″to-sin´thә-sis) a chemical combination caused by the action of light; specifically the formation of carbohydrates from carbon dioxide and water in the chlorophyll tissue of plants under the influence of light. adj., photosynthet´ic., adj.

phototaxis
(fo″to-tak´sis) taxis of cells and microorganisms under the influence of light. adj., phototac´tic., adj.

phototherapy
(fo″to-ther´ә-pe) treatment of disease by exposure to light from either the sun or an artificial source. One example is the treatment of nonhemolytic neonatal hyperbilirubinemia. ultraviolet phototherapy the use of ultraviolet radiation (which may be type A, B, or C, or ...

photothermal ablation
laser ablation of tissue in which light is absorbed by the tissue and converted to heat, resulting in coagulation, necrosis, and vaporization.

phototoxic
(fo´to-tok″sik) pertaining to, characterized by, or producing phototoxicity.

phototoxic dermatitis
a type of actinic dermatitis resembling a severe sunburn, sometimes with vesiculation, resulting in hyperpigmentation and desquamation, seen on light-exposed areas of the skin as the cutaneous manifestation of phototoxicity.

phototoxicity
(fo″to-tok-sis´ĭ-te) a type of photosensitivity that is induced by a toxic substance, in contrast to a photoallergy. See also phototoxic dermatitis.

phototrophic
(fo″to-tro´fik) capable of deriving energy from light.

photuria
(fo-tu´re-ә) excretion of urine having a luminous appearance.

phrenalgia
(fre-nal´jә) pain in the diaphragm.

phrenic
(fren´ik) diaphragmatic. mental (def. 1).

phrenic ampulla
a dilatation sometimes seen at the lower end of the esophagus.

phrenic nerve
a major branch of the cervical plexus, extending through the thorax to provide innervation of the diaphragm. Nerve impulses from the inspiratory center in the brain travel down it, causing contraction of the diaphragm, so that inhalation can occur.

phrenic pacemaker
electrophrenic pacemaker.

phrenic pacing
electrophrenic respiration.

phrenic pressure point
a point along the phrenic nerve between the sternocleidomastoid and the scalenus anticus on the right side; pressure on the point suggests gallbladder disease.

phrenicocolic ligament
a fold of peritoneum passing from the left colic flexure to the adjacent part of the diaphragm.

phrenitis
(frә-ni´tis) inflammation of the diaphragm; called also diaphragmitis.

phrenocolic
(fren″o-kol´ik) pertaining to the diaphragm and colon.

phrenogastric
(fren″o-gas´trik) pertaining to the diaphragm and stomach.

phrenohepatic
(fren″o-hә-pat´ik) pertaining to the diaphragm and liver.

phrenoplegia
(fren″o-ple´jә) paralysis of the diaphragm.

phrenotropic
(fren″o-tro´pik) exerting its principal effect upon the mind.

phronesis
(fro-ne´sis) in bioethics, the virtue of practical wisdom, the capacity for moral insight to discern what moral choice or course of action is most conducive to the good of the agent or the activity in which the agent is engaged.

phrynoderma
(frin″o-dur´mә) follicular hyperkeratosis.

phthalic anhydride
a reactive low-molecular-weight compound with various industrial uses; it causes skin irritation and its fumes cause hypersensitivity pneumonitis.

phthiriasis
(thir-i´ә-sis) pediculosis pubis.

Phthirus
(thir´әs) a genus of lice. P. pu´bis is the pubic or crab louse, a species that infests human pubic hair and sometimes other hairy areas; see also pediculosis pubis.

phthisis
(thi´sis) (ti´sis) wasting of the body. phthisis bulbi shrinkage of the eyeball.

Phycomycetes
(fi″ko-mi-se´tēz) in some systems of classification, a class of fungi comprising the common water, leaf, and bread molds and including the medically important Zygomycetes as a subclass.

phycomycosis
(fi″ko-mi-ko´sis) any of a group of acute fungal diseases caused by members of the class Phycomycetes. mucormycosis.

phyllodes tumor
a large, locally aggressive, sometimes metastatic fibroadenoma in the breast, with stroma that is unusually cellular and resembles sarcoma. Called also giant fibroadenoma of breast.

phylogeny
(fi-loj´ә-ne) the complete developmental history of a group of organisms. adj., phylogenet´ic, phylogen´ic., adj.

phylum
(fi´lәm) pl. phy´la a primary division of the plant or animal kingdom, including organisms that are assumed to have a common ancestry.

phyma
(fi´mә) a skin swelling or tumor larger than a tubercle.

physaliferous cells
physaliphorous cells spheroidal nucleated cells, containing glycogen or mucin, causing them to appear vacuolated; they are characteristic of chordoma.

physiatrics
(fiz″e-at´riks) physiatry.

physiatrist
(fiz″e-at´rist) a physician who specializes in physiatry.

physiatry
(fiz″e-at´re) the branch of medicine that uses physical therapy, physical agents, such as light, heat, water, and electricity, and mechanical apparatus, in the diagnosis, prevention, and treatment of bodily disorders. Called also physiatrics and physical medicine.

physical
(fiz´ĭ-kәl) pertaining to the body or to material things. pertaining to physics.

physical abuse
any act resulting in a nonaccidental physical injury, including not only intentional assault but also the results of unreasonable punishment.

physical allergy
a condition in which the patient is sensitive to the effects of physical agents, such as heat, cold, or light.

physical conditioning
conditioning (def. 1).

physical dependence
physiological dependence drug dependence in which the drug is used to prevent withdrawal symptoms or in which it is associated with tolerance, or both.

physical fitness
the capacity of an individual to perform physical activities requiring cardiorespiratory exertion, muscular endurance, strength, or flexibility. It is determined by a combination of genetically inherited ability and regular physical activity, and is enhanced by proper nutrition.

physical map
a gene map showing the linear order of genes or markers in the genome, along with the physical distances between them, rather than the frequencies of recombination; measured in base pairs. Cf. genetic map.

physical medicine
physiatry.

physical sign
objective sign.

physical therapist
a rehabilitation professional who promotes optimal health and functional independence through the application of scientific principles to prevent, identify, assess, correct, or alleviate acute or chronic movement dysfunction, physical disability, or pain. A physical therapist is a graduate of a physical therapy program ap...

physical therapy
the profession practiced by licensed physical therapists, defined as the examination, treatment, and instruction of persons in order to detect, assess, prevent, correct, alleviate, and limit physical disability and bodily malfunction. The practice of physical therapy includes the administration, interpretation, and evalua...

physical urticaria
acute urticaria caused by a physical stimulus such as heat, cold, sunlight, or rubbing or light scratching of the skin.

physician assistant
a health care professional who is able to perform certain of a physician's duties, serving as either an assistant to the primary care physician or as a surgeon assistant. The physician assistant has the knowledge and skill to do history taking, physical examination, drawing of blood samples, urinalysis, electrocardiograph...

Physicians' Desk Reference
(PDR) a reference book published yearly that contains drug monographs and an illustrated section for drug identification; it is also available on CD-ROM.

physicochemical
(fiz″ĭ-ko-kem´ĭ-kәl) pertaining to both physics and chemistry.

physics
(fiz´ik) the study of the laws and phenomena of nature, especially of forces and general properties of matter and energy. nuclear physics the study of atomic nuclei and their reactions.

physiochemical
(fiz″e-o-kem´ĭ-kәl) pertaining to both physiology and chemistry.