Topic 1:

Overview of How the Body’s Heating and Cooling System Operates:

The average human body contains about 5 liters of blood, which we all know is pumped by the human heart out through the arteries, veins and tissues within our bodies.  Our blood system handles many different functions on a daily basis, but for our purposes we will focus in on its function to transfer “heat” from our core to the skin’s surface, so as to maintain the normal surface temperature of 91.4F.  The body accomplishes this mission through circulation of the blood as it works to maintain a consistent body temperature through thermal regulation.  You could equate this process to what your thermostat attempts to do for your house.  The challenge of the body to maintain a consistent temperature is quite complex, due to the nature of the elements that our bodies are subjected to on a daily basis.  Our core temperatures don’t generally vary by more then a total of one degree, however are extremities or limbs can be subject to both extreme heat or extreme cold which forces our bodies to try and compensate in achieving its nature equilibrium temperature.

Our metabolism also plays an active roll in the heat generation process of the body and could be considered the boiler room that converts the caloric input of food into heat.  During intense periods of exercise, it is better to fuel the body with a higher ratio of carbohydrate calories to protein calories, because they process faster and provide a better energy output then would a higher level of protein.  The body still needs to be fed and re-stocked with a higher ratio of proteins to carbs, primarily after the intense exercise has been completed.  The metabolic rate and contribution to the heat generation process varies by individual and especially by the age of the individual.(unfortunately it slows down as we get older)

The process of heat transfer to and from the body is accomplished by four primary means:  conduction, convection, radiation and the vaporization of moisture or water.  The conduction process involves the warming of the cold air as it meets with the exposed body part, such as the skin on your hand for example.  As the cool or cold air is warmed, the warm molecules ascend away from the skin and are replaced by new cool or cold molecules.  The repetitive process continues to draw the surface heat away from the hand by air movement, with the air movement being noted as convection.  A real life example of this is holding your bare hand out unprotected in the cold Winter temperatures, where the combination of the cold temperature and the wind make your hand very cold over some period of time.  The radiation process involves the transfer of heat from one surface to another without any contact between the two.  Examples such as the heating that you may feel on your skin from the sun, or the loss of heat that you might feel from an exposed hand when you place it above snow or ice.  Vaporization of water and heat loss in cold conditions is most predominant thought breathing, however it also occurs through excessive sweating caused by the improper garment fabric characteristics being used.  The majority of the heat loss that the body experiences however, 80 to 85% still happens at the surface of the skin.

The main cooling system for the human body is the Sweat Glands.  They  are found in almost every part of the skin and are made up of a  body as well as the  part that we are most familiar with,  which is the duct that opens to the skins surface.   The natural cycle is as the body builds up excessive heat over the equilibrium temperature, the body perspires in response to the heat build up in various locations to help cool the body temperature back down again to achieve thermal equilibrium.