COOL-AID IS ON THE WAY...
In three previous posts we have learned about hot and hostile environments in general, and dived deep into hot hostile environments and how they put the body at risk of death; Then we learned how our body gets rid of heat. This post will focus on what happens to the human body in cold hostile environments, mechanisms of heat conservation, and mechanisms of heat production.
A cold environment could be defined as one in which the environment’s temperature is
lower than that of the body, while a hostile and cold environment could be defined as one in which the environment’s temperature is significantly lower than that of the body, which could put one’s health/life in danger. in addition, cold hostile environments tend to be challenging as it pertains to water and food resources, more so food than water (ice is made of water).
The basic principle behind the idea of existence and/or exercise in a cold environment is one of a simple temperature gradient with three optional outcomes: 1) The environment is hotter than the body - the body takes in heat; 2) The body is hotter than the environment - the body loses heat; 3) The body is equal in temperature to that of the environment - heat does not change its location.
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While this next point might be counter-intuitive to some, there is no such real thing as "cold" rather than the lack of heat. In order to create "cold" conditions, we get rid of heat or heat is eliminated. This is similar in essence to the idea of light and dark. There no such real thing as darkness, rather the absence of light. You reduce or eliminate light, thus create "darkness". Both cold and darkness are the passive outcomes of active processes eliminating or reducing heat and light accordingly.
Cold environments create a natural and passive temperature gradient, where heat moves according to the gradient create from areas with high temperature, to areas with low temperature. Since the body is hotter than the environment in cold or cold hostile environments (by definition), heat will leave the human body, and translocate to the environment, unless prevented from doing so.
The main ways to prevent this gradient from happening are to 1) Create less heat; 2) Prevent heat from engaging with the environment (insulation and isolation; via natural or external means). In other words, since heat is created, as it must naturally be created to an extent that keeps us alive, the true "name of the game" is to prevent its loss to the environment (i.e. insulation and isolation). Heat creation is called thermogenesis (thermo = heat; genesis = creation).
As structure determine function (one of the most basic rules/principles of the living and nature), we tend to lose heat to the environment through our hands, feet, and head, if they are exposed to the environment and not insulated nor isolated. Since sweating is a means of heat disposal, a process we wish to eliminate as needed, sweat production is decreased to a minimum as fits the functional needs. Please remember that too much insulation and isolation could result in the over-heating of the body, and be equally and perhaps more dangerous in some cases.
Hair is erected in order to try and capture heat, blood flow to the skin is reduced to the minimum via vasoconstriction, meaning the narrowing of blood vessels, by reducing their radius. Extreme vasoconstriction as utilized in hostile environment, will lead to numbness, pain, and possible loss of blood circulation to that specific area. The bigger the blood vessel undergoing vasoconstriction, the more tissue influenced.
The cells of our body contain about 60% of the total water volume of the body. Water is water, is water, water. Thus, cells that are exposed to extreme cold conditions could literally freeze from the inside-out. The water within the cells is water the same as any other water, and will freeze, causing the cells themselves to freeze. This is part of the phenomenon known as "frostbite", characterized by crystals forming within the cells as they freeze. At this point, the cells become more and more dysfunctional, until they are completely dysfunctional.
In order to warm up, the body initiates heat production hormonally, also known as metabolic heat production. Shivering is preferred over regular movement as much as possible, as it produces a more favorable ratio between heat production and heat loss. The “command” to shiver is hormonal and directed to the skeletal muscles. Since muscles can produce force isometrically, they can also work inefficiently to "waste" energy in the sense if shivering, the increases friction, that becomes heat.
High frequency shivering uses glucose as fuel, while low frequency shivering uses fat. Brown adipocytes (“brown fat” cells) are catabolized in order to create heat without muscle shivering (non-shivering thermogenesis), a reaction to hypothermia, when the body's core temperature is less than 95°F which is the same as less than 35°C.
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Symptoms due to the possible negative influences of a cold hostile environment may include (not limited to):
Confusion and irrational behaviors
Liver dysfunction
Amnesia
Slurred speech
Decreased reflexes
Loss of fine motor skills
Inflamed skin
Hallucinations
Fixed dilated pupils
Low blood pressure
Pulmonary Edema
Increased combativeness
Due to confusion and irrational behavior, people often take off their cloths, even though they are literally freezing. The nervous system is very sensitive to temperature changes, leading to dysfunction as a result. A dysfunctional nervous system can put a person in danger and/or prevent them from saving themselves by not being able to "tap" into common sense and/or actual knowledge. The next post will be dedicated to how cold hostile environments can cause a death trap, similar to the one we saw created in hot hostile environments.
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