You Lose Most of Your Heat

Through Your Head!

FACT

MYTHor

What is body heat? Where is it produced?Body heat is the byproduct of the body’s normal metabolism.

As energy sources are broken down such as proteins, sugars, and fats, they are metabolized to produce ATP.

As this process takes places some of the energy is lost as heat.

What is the body’s temperature at homeostasis?

98.6 degrees Fahrenheit =37.0 degrees Celsius

There is .9 degrees Fahrenheit Fluctuation/.5 degrees Celsius

What causes the body temperature to

fluctuate?

Estrogen

Progesterone

Contraceptives

Seasons??

What happens when your body heat

changes?

FLUSHING

Shivering

-Capillary dilation

-Groups of muscle contractions

How does the human body lose heat?

RADIATIONCONDUCTION

EVAPORATION

????????????????????

Too hot?

RADIATIONand

EVAPORATION

Too cold??

CONDUCTION

How much heat does the human body release daily?

Boron & Boulpaep's Medical Physiology says that `the body's rate of heat production can vary fom

approximately 80 kcal/h [93 Watts] at Rest to 600 kcal/h [697 Watts] during jogging'.-radation=60%

What is it when it’s too high?

An early morning temperature higher than 37.2 degrees Celsius (98.9 degrees Fahrenheit) or a late afternoon temperature higher than 37.7 degrees Celsius (99.9 degrees Fahrenheit) is normally considered a fever.

FEVER!

What is it when it’s too low??

-when the body's core temperature drops by 1-2 degrees Celsius (1.8-3.6 degrees Fahrenheit) below normal temperature.

HYPOTHERMIA

If you can’t take the heat,stay out of the

kitchen……

SURFACE AREAvs. “The HEAD”

13-16% of the blood’s volume is located in the head.The head accounts for 10% of the body’s total surface area, therefore it only accounts for a small

portion of the body’s radiation.According to “Wilderness Medicine” , the head only accounts for 7% of the body heat that is lost, and that rate of heat lost is the same for any exposed body part. =MYTH

CNN votes “MYTH”CNN published an article of 10 health myths, and this article threw out the belief that “75% of body heat is lost through ones head”.

: “This adage was probably based on an infant’s head size, which is a much greater percentage of the total body than an adult head”. That’s why it’s important to make sure an infant’s head remains covered in cold weather. (This also explains those ubiquitous newborn caps at the hospital.) But for an adult, the figure is more like 10 percent. And keep in mind that heat escapes from any exposed area (feet, arms, hands), so putting on a hat is no more important than slipping on gloves.

Dr. Sessler agrees on HAUX!!!

“The face, head and upper chest are up to five times as sensitive to changes in temperature as other areas. This creates the illusion that covering up those areas traps in more heat, but clothing another part of the body does just as much to reduce overall heat loss”

If you compare the results from someone wearing a swimsuit, to someone fully clothed, but only missing a hat, the results would remain the same. The head would still only account for a SMALL portion of the body heat that is lost.

MYTH

The origins of this hat-wearing myth were traced back to 1970 when a US army survival guide recommended that the soldiers cover their heads since “40-45 percent of body heat” is lost through the head.

Rachel Vreeman and Aaron Caroll of the “British Medical Journal” stated that if the myth was “rubbish”, and if it were true then “humans would be just as cold if they went without a hat as if they went without trousers. ‘Patently, this is just not the case,’.”

The head hands and feet in fact are just more sensitive to heat loss, which makes people feel like they are preventing loss when they cover up.

RUBBISH

The bottom line is it’s aMYTH!!

What did you learn today?

1. The head loses heat faster than any other body part because it contains 13-16% of the body’s blood volume.

A.TRUE

B.FALSE

2. How much of the body’s radiation does the head account for?

A. 13-16%B. 10%C. 7%

ANSWERS:

1.B. FALSE

2.C. 7%

REFERENCES• Centers for Disease Control., (2007) Winter Weather:

Hypothermia. Emergency Preparedness and Response. Retrieved from

• http://emergency.cdc.gov/disasters/winter/staysafe/hypothermia.asp

• E. McKenzie, D.W. Osgood, Validation of a new telemetric core temperature monitor, Journal of Thermal Biology, Volume 29, Issues 7–8, October–December 2004, Pages 605-611, ISSN 0306-4565, doi 10.1016/j.jtherbio.2004.08.02

•  Dodd SR, Lancaster GA, Craig JV, Smyth RL, Williamson PR (April 2006). "In a systematic review, infrared ear thermometry for fever diagnosis in children finds poor sensitivity". J Clin Epidemiol 59 (4): 354–7.

• Kelly GS (March 2007). "Body temperature variability (Part 2): masking influences of body temperature variability and a review of body temperature variability in disease". Altern Med Rev 12 (1): 49–62. PMID 17397267