Your skin is the largest organ of your body. What? You think I'm insane - or maybe drunk? Perhaps you may want to explain how come that single, unbroken, dermal sheet wraps around and covers all other organs, including the entire skeleton, within its shroud! Well, besides keeping all those organs tucked in and preventing all those fluids from spilling out, the skin has a very significant role in the body's thermoregulation process. So, how does the skin help to regulate body temperature? Well, before I spill the beans about that, what would you say to familiarizing yourself with a few basics about normal body temperature and crucial aspects of thermoregulation? If your answer is in the affirmative, read right ahead.
Normal Body Temperature and Regulation
The normal human body temperature reading, if measured from the mouth using an oral thermometer, comes to 98.2°F with a maximum variation of 1.3°F above or below it. This figure is always slightly higher than the temperature measured from skin (usually by placing a thermometer inside the armpit) which usually hovers around 97.9°F. These are average values and somewhat wide variations are not uncommon. Any axillary temperature (measured from armpit) reading varying within the range of 96°F-99°F is considered normal.
The maintenance of normal body temperature and preventing it from increasing or decreasing drastically in response to a dramatic rise or dip in the atmospheric temperature is extremely essential for the normal functioning of the body and all internal organs. Any inappropriate rise (hyperthermia) or fall (hypothermia) in body temperature beyond the normal limits for a significant duration owing to body temperature regulation problems can lead to organ failure and death.
Therefore, in order to maintain normal body temperature even in the face of drastic changes in atmospheric temperature, the body performs certain functions that help it to regulate thermal stability and maintain the right amount of heat. It does so by cooling itself to avoid abnormally high body temperature when in a hot external environment temperature and by conserving heat to avoid dangerously low body temperature when in a very cold external environment.
Role of Skin in Thermoregulation
The skin is quite an interesting organ. As simple as it may look to the eye, a cross-sectional view will reveal its true, intricate structure. The two structures that are parts of the entire dermis and help in the regulation of body temperature, especially in mammals, are the sweat glands and the insulating fatty layer that is present on the inner side of the dermis. When the external temperature is hot, the sweat glands get activated and release the salty, transparent fluid that we call perspiration.
When this sweat comes out of the pores in the skin and comes in contact with air on the outer surface, it evaporates, thereby, cooling the body from the outside. In furry mammals, sweating is not a primary cooling option due to the presence of a fur coat on the outside. Such mammals resort to panting - allowing saliva and body moisture to evaporate from the moist surface of the mouth and tongue - in a bid to release excess heat and bring down body temperature close to normal levels.
Now, coming to the heat conservation part, the fat layer that is present on the inner side of the dermal cover acts as an insulation, preventing heat from escaping to the skin surface. This helps the body to retain all the heat it can during cold weather and low external temperature conditions. The presence of furs and feathers on the skin further help the body to trap as much heat as possible.
This is the reason why most creatures that inhabit cold and polar regions have thick fur and lots of body fat. Whales inhabiting the cold polar seas have a thick layer of fat, known as blubber, on their insides which keeps their bodies from freezing in the harsh cold and wet environment of their habitat. So, the skin helps to regulate body temperature by releasing and conserving heat as and when necessary - that, precisely, summarizes it!