When All Hell Breaks Loose (16 page)
Read When All Hell Breaks Loose Online
Authors: Cody Lundin
The term "exposure" is a generic term often used by the media to describe deaths due to
hypothermia
or
hyperthermia
. Both are, by far, the unspoken causes of death that in silence and without fanfare go about killing the unprepared en masse around the world. Please realize that many of the skills and concepts presented in this book are directly or indirectly related to helping you achieve and maintain a normal core body temperature for your survival. The following information on body temperature regulation is extremely important, so don't space out and go on autopilot when you read it. The most efficient way to prepare for and mitigate a disaster is to know its cause.
Thermoregulation: Your Body's Nitty Gritty for Both Country and City
In humans, core body temperature alternates in cycles throughout the day. While daily activity is responsible for some of this cycling, the body's
circadian rhythm
accounts for the majority. Inner body temperatures are lower in the early morning, around 97.9 degrees (36.6 degree C) with the late afternoon high being approximately 99.3 degrees (37.4 degrees C). Age is also an important factor, as some thermoregulatory responses are not fully developed until after puberty. People in their sixties and older will be subject to less sweating in reaction to heat and a reduced vasoconstrictor response and shivering in response to cold. While body temperature regulation between men and women is similar, there are several subtle differences in females. Females have a smaller blood volume, lower hemoglobin concentration, smaller heart and lean body mass (less muscle means less shivering), a greater percentage of total body fat, greater surface area to mass ratio, a higher body temperature set point for sweating, and geometrically thinner extremities, to name a few. Females also have the added difference of monthly temperature variations relating to menstrual cycle, pregnancy, and menopause.
Fluctuations in core body temperature, high or low, of even a few degrees can severely compromise your ability to survive
. To control its inner temperature, the body must be able to sense a change in environmental temperature and respond accordingly. To do so, in part, the body is equipped with
warm
and
cold receptors
located in the skin, spinal cord, muscles, and brain that begin physiological changes to quickly deal with temperature extremes. Many variables contribute to the development and severity of hypothermia and hyperthermia including a person's age, sex, health, nutrition, body size, hydration, physical exercise, exhaustion, duration of exposure to wind and temperature, wetness, medications, intoxicants, and prior adaptation to heat or cold. The core body temperature is thermoregulated by the physiological responses and reflexes of
vasoconstriction, vasodilation, shivering
, and
sweating
. Aside from basic physical necessities such as an unobstructed airway, breathing, and circulation, thermoregulation is of prime importance for your short- and long-term survival.
Temperature regulation in humans represents the balance between
heat production
from metabolic sources such as digesting a pizza and exercise, and
heat loss
from respiration and evaporation (sweating) and the physics of radiation, convection, and conduction. Once hypothermia develops, the heat deficit is shared by two body compartments, the shell and the core. Your outer skin or "shell" consists of .065 inches of skin and has an average area of 2.2 square yards. This means that on average your shell accounts for only 10 percent of your total body mass. The rest of it is considered "the core." In other words, when your body senses a drop in core temperature, it burns through an enormous amount of calories and puts a dent in your stored food supply.
Human beings suck in their ability to physiologically adapt to
cold
environments. Temperature regulatory mechanisms act through the autonomic nervous system and are largely controlled by the hypothalamus. The hypothalamus responds to stimuli from nerve receptors in your skin, which is the largest organ in your body. In a cold environment, body heat is conserved first by the constriction of blood vessels near the body's surface (vasoconstriction), keeping the majority of blood (heat) in the core. The body thus uses the skin and underlying fatty layer as insulation. The one area of skin that doesn't constrict blood flow when the outside temperature gets cold is the scalp, which likes to remain at a fairly constant temperature regardless of outside extremes. This is one reason why the head and neck area loses (and gains in hot temperatures) a tremendous amount of heat.
In its attempt to regulate temperature, the body changes blood flow to the skin. When blood vessels are dilated wide open in hot weather, the body can circulate more than four quarts of blood every minute—in the skin alone. In cold weather, blood vessels constrict the skin's blood flow to an amazing 99 percent of the former, a mere 0.02 quarts per minute! Ironically, when temperatures continue to drop, blood vessels in the skin dilate (vasodilation), and if temperatures drop further, the blood vessels alternate back and forth between dilation and constriction in the body's attempt to ensure that the skin remains undamaged from the cold. The result is your red nose, ears, hands, and other appendages in the wintertime. If outside temperatures continue to plummet, however, surface blood vessels constrict continuously to protect the core.
Second in the body's response to cold are uncoordinated waves of muscle contractions more commonly referred to as
shivering
. Shivering utilizes small parts of the skeletal muscles called motor units, which contract at around ten to twenty times per second and can increase your metabolism fivefold! The energy needed for shivering comes from fats and simple sugars (carbohydrates) and can be used up quickly if not replaced with extra food. Shivering
decreases
when carbon dioxide levels raise (as in a poorly ventilated home or emergency shelter), when the oxygen in the air becomes thinner (extremes in altitude), and through the use of alcohol, which impairs the shivering response.
Since blood vessels are essentially the pipes your body uses to heat itself by forcing warmed blood throughout your body, ingesting substances that dilate surface blood vessels is stupid. Purposely constricting blood vessels is also a bad move whether through nicotine use, dehydration, or tight clothing. Dehydration slowly turns your blood into ketchup, making it that much harder for the heart to circulate the sludge around in order to keep inner temperatures stable. Low temperatures also change the composition of blood, making it thicker by up to 21 percent, by increasing the number of particles such as platelets, red blood cells, and cholesterol.
When it's
hot
outside, heat must be lost by the body to maintain a proper core temperature. Brain cells are particularly sensitive to high temperatures. Increased surface blood flow through dilated vessels, especially in the arms and legs, works at dissipating extra heat by exploiting the major surface areas of the body as well as avoiding the insulating properties of subcutaneous fat. Once again, if your blood turns to ketchup because of dehydration, this activity is severely compromised. The increased surface blood flow and the wonders of evaporative heat loss through increased sweating are the main tools your body uses to stabilize its inner core when outside temperatures soar.
Cellular Chaos
Your body's 50 billion cells have permeable membranes, or "walls," consisting of lipids or fats. Through these membranes cells make and break bonds at precise rates, maintaining such levels as our sodium and potassium balance. These membranes, being composed of fats, are very sensitive to changes in temperature.
When your core body temperature drops, proteins within the cells start to clump, causing holes, while water in and around the cells freeze to form jagged ice crystals that shred the delicate membranes. Conversely, as the core overheats, cell membranes begin to lose their elasticity and can actually melt. With cell membranes damaged, precision rates are altered and once-pristine body systems fall into a state of unregulated pandemonium.
Fluctuations in core body temperature literally cause chaos on a cellular level, chaos you can see in the uncoordinated signs and symptoms of hypo- and hyperthermia
.
In summary, living in
cold temperatures
without insulated clothing and footwear, lying on uninsulated ground (conduction), or wearing weather-dampened or sweated-out cotton clothing (evaporation) in the wind (convection) while being unable to improvise a heat source (radiation) can all cause death by hypothermia.
Conversely, in
hot temperatures
,
radiation
from the sun (directly and reflected from the ground and particulate matter in the air) can heat up
conductive
ground surfaces in excess of 150 degrees F (65.5 degrees C). This in turn helps produce heated
convective
winds capable of
evaporating
sweat obscenely fast with little cooling effect for the body. Add in the effects of
metabolic heat
produced by digging a sanitation trench in the backyard at noon, and you have a serious setup for dehydration, hyperthermia, and death.
Knowing the Signs and Symptoms of Hypothermia and Hyperthermia
A "sign" is a behavior you see in someone else while a "symptom" is a behavior someone else sees in you. Notice that the psychological signs and symptoms of hypothermia and hyperthermia are very similar, involving disorientation and poor coordination. These similarities are no accident and offer vital clues into a person's physiology at the time.
In city or country, recognizing the signs and symptoms of hypothermia and hyperthermia in yourself and others is critical as they are the body's warning signals that things are getting out of whack on a cellular level
. The majority of people dead from exposure had ample early warnings that were ignored. These warning signs are your second chance to immediately manipulate your internal and external environment in whatever way you can to prevent further heat loss or gain.
Heinous Hypothermia: The Signs and Symptoms
Early Signs and Symptoms
Core temperature 95–96 degrees F (35–35.5 degrees C)