| utricular spot | The neuroepithelial sensory receptor in the inferolateral wall of the utricle; hair cells of the neuroepithelium support the statoconial membrane and have terminal arborizations of vestibular nerve fibres around their bodies; sensitive to linear acceleration in the longitudinal axis of the body and to gravitational influences. Synonym: macula utriculi, utricular spot. (05 Mar 2000) |
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| flying spot microscope | <instrument> A microscope in which a moving spot of light is imaged in the object plane, the energy transmitted by the specimen being detected with a photoelectric cell; the light source may be a cathode ray tube, a scanning disk or drum, or an oscillating mirror. (05 Mar 2000) |
| focal spot | The site of bombardment by electrons and emission of X-rays from the anode of an X-ray tube. See: focal spot size. (05 Mar 2000) |
| focal spot size | The measured size of a focal spot, a function of its actual size and the angulation of the anode surface. See: focal spot. (05 Mar 2000) |
| forty-spot | <zoology> The Tasmanian forty-spotted diamond bird (Pardalotus quadragintus). Source: Websters Dictionary (01 Mar 1998) |
| Fuchs' black spot | An area of pigment proliferation in the macular region in degenerative myopia. (05 Mar 2000) |
| liver spot | A variably pigmented lentigo occurring on exposed skin of older Caucasians. Synonym: liver spot, solar lentigo. (05 Mar 2000) |
| abdominal pressure | Pressure surrounding the bladder; estimated from rectal, gastric, or intraperitoneal pressure. (05 Mar 2000) |
| absolute pressure | Pressure measured with respect to zero pressure. Compare: gauge pressure. (05 Mar 2000) |
| acoustic pressure | In ultrasound, the instantaneous value of the total pressure minus the ambient pressure; unit is pascal (Pa). (05 Mar 2000) |
| air pressure | The force per unit area that the air exerts on any surface in contact with it. Primarily used for articles pertaining to air pressure within a closed environment. (12 Dec 1998) |
| atmospheric pressure | The pressure at any point in an atmosphere due solely to the weight of the atmospheric gases above the point concerned. (12 Dec 1998) |
| back pressure | Pressure exerted upstream in the circulation as a result of obstruction to forward flow, as when congestion in the pulmonary circulation results from stenosis of the mitral valve or failure of the left ventricle. (05 Mar 2000) |
| back-pressure renal atrophy | <radiology> Caliectasis without obstruction, due to repeated episodes of obstruction, gradual loss of renal pyramids (12 Dec 1998) |
| barometric pressure | The absolute pressure of the ambient atmosphere, varying with weather, altitude, etc.; expressed in millibars (meteorology) or mm Hg or torr (respiratory physiology); at sea level, one atmosphere (atm, 760 mm Hg or torr) is equivalent to: 14.69595 lb/sq in, 1013.25 millibars, 1013.25 × 106 dynes/cm2, and, in SI units, 101,325 pascals (Pa). Synonym: atmospheric pressure. (05 Mar 2000) |