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Normal body temperature and its variations

Normal body temperature is 36.6 to 37.2 or 98 to 99 degree farenheit

What are the alteration in body temperature?
The normal diurnal variation is 1°F.The normal body temperature is more towards the evening as as a result of increased BMR and increased skeletal muscle activity. Rectal temperature is 0.6°C (1°F) higher than oral temperature. Oral temperature is 0.6°C (1°F) higher than temperature recorded in the axilla.

Maximum normal oral temperature
At 6.00 AM 37.0°C (98.6°F)
At 6.00 PM 37.6°C (99.6°F)
Normally the rectal temperature > oral temperature > axillary temperature.

It is an elevation of body temperature above the normal circadian variation as a result of the change in the thermoregulatory centre, located in the hypothalamus

What are the physiological variation of temperature?
In a menstruating females, the early morning temperature recording is subnormal in the two weeks preceding ovulation. At the time of ovulation, the temperature
increases  by about 0.6°C (1°F), and it persists till menstruation occurs because of the thermogenic property of progesterone.

With every 1°F rise of temperature, above 100°F the following alterations are noted 
  • The pulse rate increases by 10, 
  • The respiratory rate increase by 4, 
  • BMR increase by 7. 
  • Oxygen consumption increases by 13%.