Body temperature in detail
The human body temperature is relatively constant, the normal body temperature fluctuates slightly in 24 hours, the general difference less than 1 degree. Under physiological conditions, the morning temperature slightly lower, at a slightly higher. After eating, exercise,menstrual period before or during pregnancy body temperature is slightly higher, while the elderly low body temperature. The temperature is higher than normal called fever, from 37.5 to 38 degrees C for low, from 38 to 39 degrees C for moderate fever, from 39 to 40 degrees Celsius as hyperthermia, more than 40 degrees Celsius and super high fever. Body temperature relatively constant is to maintain the body's normal life activity is one of the important elements, such as body temperature above 41 degrees C or less than 25 degrees will seriously affect the system ( especially the nervous system ) function activities, even endanger the lives. The heat production and heat dissipation, is affected by central nervous system regulation, many diseases can make a normal body temperature regulation function obstacles and make the temperature change. Clinical observation on the patient to check temperature, the variation in the diagnosis of disease or to judge the prognosis of certain diseases is important.
The normal body temperature of 37 degrees C, from the 1868 Uhde Leigh F on 2500 adults axillary temperature average. The United States of America Mali Lanzhou School of medicine Mike Vick detection of 148 human oral temperature is an average of 36.8 degrees Celsius, the results show that: individual normal temperature range up to 2.7 degrees C, each a day in different time temperature may be a difference of 0.6 degrees C, normal human body temperature and the lowest at 6 in the morning, afternoon 4 when highest. A temperature of 38 degrees Celsius is generally low, 38 degrees C above high fever that is.
The normal fluctuations
In one day, the body temperature of periodic fluctuation. In the morning when the minimum temperature of 2-6, 1-6 in the afternoon when the top. Wave amplitude is generally not more than 1 DEG c.. Temperature of this circadian cycle known as the circadian rhythm or day cycle.
Woman with a basal body temperature with menstrual cycle changes. In the ovulation after elevated temperature, elevated body temperature continues to the next menstrual start. This phenomenon is likely related to the sex hormone secretion. Experiments show that, this change of blood progesterone and its metabolites change coincided with.
Temperature is related to age. Generally speaking, the higher the temperature of children, newborn and older low body temperature. Newborn, especially in premature infants, due to temperature adjustment mechanism development is not perfect, thermoregulation ability is poor, so their body temperature is easily affected by the environmental temperature. Therefore for newborns should strengthen nursing.
Muscle activity metabolic heat production and enhance, increase, the results can lead to elevated temperature. Therefore, clinical should allow the patient to quiet for a period of time after the body temperature measurement. Determination of temperature should be to prevent the crying.
In addition, emotion, mental stress, eating and other conditions on body temperature will have the effect of environmental temperature on body temperature; also have influence on body temperature; Determination of, on account of these circumstances.
Heat balance
The body metabolism of nutrients release of chemical energy, of which more than 50% in the form of heat is used to maintain the body temperature, the remaining less than 50% of the chemical energy load to ATP, after energy conversion and utilization, eventually into heat energy, and maintain the temperature of heat by conduction, circulating blood to the body surface and the distribution of in vitro. Therefore, the temperature regulation mechanism under the control, so that heat production process and cooling process in balance, the body heat balance, maintain normal body temperature. If the heat is greater than the heat dissipating capacity, the body temperature will rise; heat dissipating capacity is greater than the heat production, the body temperature will drop, until the heat production and heat flux rebalancing will make the temperature stability in the new level.
Cooling process
Human body's main radiating parts of the skin. When the environment temperature below body temperature, most of the body heat through the skin of the radiation, conduction and convection heat transfer. A part of heat through the skin sweat evaporation to radiate, respiratory, urination and defecation can also be a small part of the heat dissipation.
Radiation ( radiation ): This is the body heat to heat radiation in the form of heat to the outside of a cold substance a radiating form. In this way, the heat from the body, in a quiet state a larger proportion (about heat dissipation quantity 60% the left and right sides ). Radiation heat loss and the temperature difference between the skin and the environment as well as the effective radiating area and other factors. Skin temperature fluctuations, radiative heat loss will have great change. Limb surface area is larger, so it plays an important role in radiation. Temperature and skin temperature difference is greater, or the effective radiating area is bigger, more radiation heat flux.
Conduction ( conduction ) and ( convection ): convection radiating heat conduction is the body's heat is directly transferred to come in contact with it 's colder object in a cooling mode. The deep heat conduction mode to the surface of the skin, and then by the latter passes directly to touch with the object, such as a bed or clothes. But as a result of these substances is a poor conductor of heat, so the body heat by conduction and lost a small amount. In addition, the heat conductivity and low body fat, obesity subcutaneous fat is more, women usually subcutaneous fat is more also, so, they from deep to surface conduction heat dissipating capacity be less. Skin coating fats, can also reduce the heat dissipation function. Water conductivity of bigger, according to this truth can use ice bag, ice cool to patients with high fever.
Convection heat transfer by means of gas or liquid or a way to exchange heat. Human is always around with a thin layer of skin contact with air, the body's heat to this layer of air, because air constant flow ( convection ), the body heat to space. Convection of heat conduction is a special form of. The heat loss by convection by how much, affected by wind speed greatly. Larger wind, convection heat dissipating capacity is more also, on the contrary, wind is small, convection heat dissipating capacity is less.
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