Your body is just like your house, which has an internal thermostat that it uses to regulate your internal heating and cooling. This system is mostly influenced by two systems, the integumentary and the circulatory system. The Human Body is over 70% water and the skin (a water-tight collection of "dead" cells at its surface) helps keep this percentage within acceptable ranges. This narrow percentage range of acceptable values between fluid and tissue is necessary to maintain a proper acidic environment for various chemical reactions that sustain life.
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In the human body, water lubricates joints and organs. It maintains muscle tone. Water keeps skin soft. |  |
The Integumentary System consists of skin, hair, and nails. Hair and nails have little to do with Emergency Medical Services (in spite of the fact that some females "believe" that a 'bad hair day' or 'broken nail' constitutes justification for calling an ambulance.) The skin is the largest organ in the human body and that fact, coupled with its anatomical and physiological complexity, practically warrants its treatment as a separate organ system.
The skin serves three purposes.
- Environmental protection
- Temperature regulation, and
- Sensory input.
The skin also provides environmental protection from infection. This protection is breeched only when the skin is broken, highlighting the necessity for antiseptic procedures when dealing with such circumstances. Temperature control has a direct effect on metabolic rate, and metabolic rate a direct effect of the "quality" of existence. The body's metabolic process is an exothermic one, creating a significant amount of heat, and in some external environments we are subjected to higher than optimal temperatures.
Through a process of evaporation, which produces a cooling effect, as an end result of sweat production by the sweat glands in the skin, the human body can control over-heating (whether from internal or external sources,) by routing the blood into areas close to the surface of the skin, cooling the blood and carrying that 'cooling effect' back to the interior of the body. On the superior surface of the skull, where the skin is relatively thin and immediately "backed-up" by the skull, the concentration of blood vessels is relatively high, and consequently, major heat loss is experienced through that region. It is also for this reason (the concentration of blood vessels) that scalp wounds seem to bleed so profusely. When overheated (again, from either internal or external sources) the patient will exhibit a flushed or red appearance.
Please note that it is not just the production of sweat that cools the patient. The evaporation of that fluid is a necessary occurrence in the process. Consequently, a sweating patient in a humid environment, where sweat is just collecting on the skin, may still be overheated. In some external environments, patients are exposed to colder than optimal temperatures, and the skin "helps" maintain proper body temperature by first sensing the temperature variant (the same as it might if the environment were too hot,) then shunting the blood away from the exterior surface, thereby maintaining (or conserving) body temperature. Patients experiencing hypothermia (to whatever degree) will have a pale, or cyanotic appearance.
Of interest at this point, is that the skin must "sense" the temperature variant, then communicate that information to the brain, in order for the expected outcome to be exhibited. The presentations as described above are "normal" even though, under certain circumstances, they may be beyond acceptable limits. If the environment, patient history, physical exam, and/or other findings are dictating this "normal" presentation, but you "see" something else, then the "communication" ability (Nervous System) or the "sensory" ability (Integumentary System,) or sweat production ability, may be compromised.
The human circulatory system is called a Closed System because all of the blood is contained within blood vessels and does not directly bathe body tissues. Insects and other arthropods, as well as many other invertebrate animals, have Open Circulatory Systems wherein the blood flows from one or two major vessels into body sinuses to directly bathe tissues. Oxygen is transported indirectly through the body systems of arthropods through major sinus cavities. The oxygen is bound sometimes to hemoglobin and sometimes to other transport proteins such as hemocyanin (contains copper instead of iron).
The blood plasma plays a critical role in buffering the body's pH (blood pH values usually are very close to 7.3), circulating antibodies from the immune system, regulating osmotic balance, and even regulating body temperature. It is the movement of water within your cellular system that transports vital blood plasma. Blood plasma makes up 46-63 percent of the total blood volume. Water accounts for 92 percent of the volume of plasma. Without this delicate balance of water and plasma, your body would simply begin to 'overheat'.