absolute temperature

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Related to Thermodynamic temperature: luminous intensity, thermodynamic temperature scale


the degree of sensible heat or cold, expressed in terms of a specific scale. See Table of Temperature Equivalents in the Appendices. Body temperature is measured by a clinical thermometer and represents a balance between the heat produced by the body and the heat it loses. Though heat production and heat loss vary with circumstances, the body regulates them, keeping a remarkably constant temperature. An abnormal rise in body temperature is called fever.

Normal Body Temperature. Body temperature is usually measured by a thermometer placed in the mouth, the rectum, or the auditory canal (for tympanic membrane temperature). The normal oral temperature is 37° Celsius (98.6° Fahrenheit); rectally, it is 37.3° Celsius (99.2° Fahrenheit). The tympanic membrane temperature is a direct reflection of the body's core temperature. These values are based on a statistical average. Normal temperature varies somewhat from person to person and at different times in each person. It is usually slightly higher in the evening than in the morning and is also somewhat higher during and immediately after eating, exercise, or emotional excitement. Temperature in infants and young children tends to vary somewhat more than in adults.
Temperature Regulation. To maintain a constant temperature, the body must be able to respond to changes in the temperature of its surroundings. When the outside temperature drops, nerve endings near the skin surface sense the change and communicate it to the hypothalamus. Certain cells of the hypothalamus then signal for an increase in the body's heat production. This heat is conducted to the blood and distributed throughout the body. At the same time, the body acts to conserve its heat. The arterioles constrict so that less blood will flow near the body's surface. The skin becomes pale and cold. Sometimes it takes on a bluish color, the result of a color change in the blood, which occurs when the blood, flowing slowly, gives off more of its oxygen than usual. Another signal from the brain stimulates muscular activity, which releases heat. Shivering is a form of this activity—a muscular reflex that produces heat.

When the outside temperature goes up, the body's cooling system is ordered into action. Sweat is released from sweat glands beneath the skin, and as it evaporates, the skin is cooled. Heat is also eliminated by the evaporation of moisture in the lungs. This process is accelerated by panting.

An important regulator of body heat is the peripheral capillary system. The vessels of this system form a network just under the skin. When these vessels dilate, they allow more warm blood from the interior of the body to flow through them, where it is cooled by the surrounding air.
Abnormal Body Temperature. Abnormal temperatures occur when the body's temperature-regulating system is upset by disease or other physical disturbances. fever usually accompanies infection and other disease processes. In most cases when the oral temperature is 37.8°C (100°F) or over, fever is present. Temperatures of 40°C (104°F) or over are common in serious illnesses, although occasionally very high fever accompanies an illness that causes little concern. Temperatures as high as 41.7°C (107°F) or higher sometimes accompany diseases in critical stages. Subnormal temperatures, below 35.6°C (96°F) occur in cases of collapse; see also symptomatic hypothermia.
absolute temperature (T) that reckoned from absolute zero (−273.15°C), expressed on an absolute scale.
basal body temperature (BBT) the temperature of the body under conditions of absolute rest; it has a slight sustained rise during the luteal phase of the menstrual cycle and can be used as an indirect indicator of when ovulation has occurred.
body temperature the temperature of the body of a human or animal; see temperature.
core temperature the temperature of structures deep within the body, as opposed to peripheral temperature such as that of the skin.
critical temperature that below which a gas may be converted to a liquid by increased pressure.
normal temperature the body temperature usually registered by a healthy person, averaging 37°C (98.6°F).
risk for imbalanced body temperature a nursing diagnosis accepted by the North American Nursing Diagnosis Association, defined as a state in which an individual is at risk of failure to maintain body temperature within the normal range.
subnormal temperature temperature below the normal. See also symptomatic hypothermia.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

ab·so·lute tem·per·a·ture (T),

temperature reckoned in degrees Kelvin from absolute zero.
Farlex Partner Medical Dictionary © Farlex 2012

ab·so·lute tem·per·a·ture

(T) (ab'sŏ-lūt' tem'pĕr-ă-chŭr)
Temperature reckoned in the Kelvin scale from absolute zero.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

absolute temperature

Temperature expressed in the Kelvin scale with absolute zero as 0 kelvin. The magnitude of the kelvin is the same as that of the degree Celsius and any Celsius temperature can be represented as an absolute temperature by degrees C - 273.15. The term ‘degree kelvin’ is no longer used; absolute temperatures are shown in kelvins (WilliamLord Kelvin, British physicist, 1824–1907).
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
References in periodicals archive ?
The quantity that is termed temperature is well-defined by the laws of thermodynamics; measures of temperature that are defined to be consistent with the laws of thermodynamics are said to be thermodynamic temperatures. The measurement of thermodynamic temperature is based on a physical system that can be created in the laboratory and whose temperature is related to a set of measurable properties.
An alternative to CVGT is the acoustic thermometer, which again relies on a simple relationship between thermodynamic temperature and measurable properties of the gas.
11, recent acoustic thermometry results at NIST (34) have determined thermodynamic temperature with a standard uncertainty of 0.6 mK in the temperature range 217 K to 303 K.
Soulen (42) later refined this technique into a special type of JNT instrument known as an "R-SQUID," which was used to establish thermodynamic temperature between 520 mK and 6.5 mK.
The quantity realized can be either the thermodynamic temperature or a value on the ITS-90, depending on the measurement techniques (see Sec.
where [C.sub.IL] is the first radiation constant for spectral radiance, [C.sub.2] is the second radiation constant, n ([lambda]) is the index of refraction of air, and T the thermodynamic temperature of the source.
Schooley, Differences between Thermodynamic Temperature and t (IPTS-68) in the Range 230 [degrees]C to 660 [degrees]C, Metrologia 26, 95-106 (1989).
When it was developed, the ITS-90 represented thermodynamic temperatures as closely as possible.
Since that time, developments in platinum resistance thermometry have resulted in many improvements: higher purity of the Pt wire; smaller size of the Pt resistance element; supports for the Pt resistance coils that are nearly free of contamination and that maintain the Pt resistance coil in a nearly strain-free state; and increased accuracy of resistance measurements and of representation of the thermodynamic temperatures.
Edsinger, Deviation of the International Practical Temperatures from Thermodynamic Temperatures in the Temperature Range from 273.16 K to 730 K, J.
Goodwin, Thermodynamic Temperatures of the Triple Points of Mercury and Gallium and in the Interval 217 K to 303 K, J.
Reilly, Calorimetric measurement of thermodynamic temperatures above 0 [degrees]C using total blackbody radiation, in Temperature, Its Measurement and Control in Science and Industry, 4, 339-348, H.