Temperature Regulation

Definitions Core Temperature –Measured as oral, aural, or rectal temperature –Temperature of deep tissues of the body –Remains relatively constant (  1ºF or  0.6ºC) unless a person develops a febrile condition –Nude person can maintain core temperature even when exposed to temperatures as low as 55ºF or as high as 130ºF in dry air Skin Temperature –Rises and falls with the temperature of the surroundings

Definitions Core Temperature –Measured as oral, aural, or rectal temperature –Temperature of deep tissues of the body –Remains relatively constant (  1ºF or  0.6ºC) unless a person develops a febrile condition –Nude person can maintain core temperature even when exposed to temperatures as low as 55ºF or as high as 130ºF in dry air Skin Temperature –Rises and falls with the temperature of the surroundings

REGULATION OF BODY TEMPERATURE

Heat Production Laws of Thermodynamics –Heat is a by-product of metabolism Basal metabolic rate of all cells of the body Effect of muscular activity on metabolic rate Effect of endocrinology on metabolic rate (i.e., thyroxin, growth hormone, testosterone) Effect of autonomic nervous system on metabolic rate

Heat Loss How fast is heat transferred from deep tissues to the skin How rapidly is heat transferred from the skin to the surrounding environment

How Fast Is Heat Transferred From Deep Tissues to Skin Insulation Systems –Skin and subcutaneous tissue (i.e., fat) Blood Flow –Cutaneous circulation

How Fast Is Heat Loss From the Skin to the Surrounding Environment Radiation Conduction Evaporation

Definitions Radiation –Loss of heat by infrared heat rays (5-20  m or X wavelength of visible light) Conduction –Loss of heat from the body to a solid object Evaporation –Loss of heat from the body through water vapor to the surrounding atmosphere Convection –Effects of changes in the external environment (e.g., wind and water)

“Wind Chill Factor” Effect of wind on skin temperature – temperature of calm air that would produce equivalent cooling of exposed skin Cooling effect of air convection equals the square root of the wind velocity –For example, air temperature feels twice as cold at a wind velocity of 4 mph than if the wind velocity is 1 mph

ºF = T V( ) V( )