core temperature


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temperature

 [tem´per-ah-chur]
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.

core temperature

Etymology: L, cor, heart, temperatura
the temperature of deep structures of the body, such as the liver, as compared to that of peripheral tissues.

core temperature

The temperature at which vital organs (e.g., brain, heart) are maintained; it is practically measured sublingually (where it is 0.25 to 0.5ºC cooler than when measured by probes in the oesophagus, nasopharynx or rectum). The core temperature of the human body is usually between 36–37.5ºC, with daily variation (lowest in the early hours of the morning) and monthly variation in women during ovulation.

core tem·per·a·ture

(kōr tem'pĕr-ă-chŭr)
The temperature of the interior of the body.

core temperature (Tc )

the mean temperature of the tissues of organisms at a depth below that directly affected by a change in the AMBIENT temperature. Tc cannot be measured accurately and is generally represented by a specified body temperature, e.g. rectal and cloacal temperatures.

body temperature

is normally regulated so as to maintain a core temperature, that of the blood and the internal organs, of 37°C ± 0.5-1°C. Determined by the balance between metabolic heat production (varying with muscular activity) and heat loss (from the skin surface, in expired air and with the excreta). Heat loss is influenced by external factors (ambient temperature, humidity, air movement and clothing) and regulated physiologically by the hypothalamus, via the autonomic nervous system, in response to changes in blood temperature and afferent information from skin receptors. Constriction or dilatation of skin blood vessels varies the skin temperature and hence the heat loss, effectively changing the thickness of the insulating 'shell' around the 'core'. Sweating is stimulated for additional evaporative heat loss and shivering for additional metabolic heat production. See also heat illness, hypothermia.

core tem·per·a·ture

(kōr tem'pĕr-ă-chŭr)
The temperature of the interior of the body.
References in periodicals archive ?
This heated blood is returned to the heart via the venous system and then redistributed throughout thus increasing the core temperature.
They found a positive correlation between Ad/mass ratio and core temperature not only for warm-humid or jungle climates, but also for neutral and hot-dry (desert) climates.
The majority of studies examining brain temperature use rectal temperature as the measurement of core temperature.
Continuous core temperature monitoring has been a challenge for caregivers due to lack of access to accurate and comfortable measurement devices designed specifically for very low birth weight preemies.
It might help to know that core temperature controls sweating and dehydration while skin temperature controls how we feel.
Once acclimated, you lose less sodium in your sweat, there is an increase in the volume of sweat you produce and the rate at which you sweat, and you start sweating at a lower core temperature.
Although Howkins' core temperature remained stable as she hiked to shelter, if it had dropped by two degrees, her hypothalamus would break down, sending her body into the first stages of hypothermia (see The 3 Stages of Hypothermia).
In heat stroke, as the core temperature of the body rises rapidly, the brain will dilate the blood vessels in the skin to attempt to cool the blood.
Remember to include a warm-up period (3-5 minutes of light, continuous, aerobic type work) to raise the body's core temperature before engaging in high-intensity, anaerobic activity.