Inadequate Heat Regulation

One of the most delicate operations in human functioning is the maintenance of a constant body temperature, higher as a rule than that of the surrounding air. The normal temperature of 98.6U+00B0 F. represents the high oxidative rate required for efficient metabolism in bodily tissues. It is maintained by the proper exchange of energies through the skin. This exchange is known as heat regulation. It consists in both the production and the liberation of heat. When the environmental temperature is less than that of the body heat loss must be decreased and heat production increased. When the environmental temperature is less than that of the body, heat loss must be increased and heat production decreased. Sudden changes in environmental temperature or bodily temperature produce a condition of inadequate heat regulation in the skin, giving rise to restless activity which continues until the two temperatures are equilibrated.

Let us examine in some detail the mechanism responsible for such excitants, as well as the manner in which they are relieved. As bodily tissues metabolize, they give off heat. The amount greatly exceeds that required to maintain efficient operation, and much of it is consequently released. The loss may occur in a number of ways; but the chief means are provided by evaporation, conduction, and radiation from the skin. Over 87 per cent of the total daily loss occurs in this fashion. When the rate of release becomes excessive, due to an inner chill of disease or an outer frigid temperature, afferent nerve endings in the skin are excited; and these arouse the neuromuscular mechanism to general activity. In cold weather such general activity is directly effective in bringing about a more favorable temperature balance, for the muscular contractions produce heat which somewhat offsets that lost by radiation. But this is not the only nor the most effective means at hand. General activity in and of itself will not entirely relieve the tissue conditions induced by frigid climate and inner chills. Loss of heat is chiefly regulated by the use of appropriate clothing. This captures a layer of warm, more or less stationary air between it and the skin. Since air is a poor conductor of heat, loss by radiation is greatly diminished.

That general activity will not itself equilibrate inadequate heat exchange is seen clearly in the case of torrid climate and inner fevers. Both of these situations cause an insufficient radiation of bodily heat and give rise to the same type of restless behavior as occurs in the case of excessive heat loss. This behavior of itself only aggravates the tissue condition calling it forth; but after it becomes directed along certain lines, such as the removal of excess clothing, the selection of cooler environment, etc., the tissue condition is relieved and the activity subsides. We so often use the device of putting on more clothes for a cold day and taking them off when it is warm that we forget that the response is probably built upon this early pattern of excess activity. According to the protective theory of the origin of clothing and shelter, primitive man was impelled to random movement by some basic motivational excitant from the skin. This activity soon became specifically directed to the seeking of clothing and shelter. For example, as primitive man moved about, he found that certain places gave relief from the outer chill; and thus he became a cave dweller. Movements involved in carrying his prey close to his body also brought relief and caused restlessness to subside. From such crude beginnings, according to this theory, our elaborate modes of dress and housing were acquired.

The relation between climatic conditions and the amount of initiative displayed by man can perhaps be referred to this same condition. The poverty of cultural development in the torrid and frigid zones of the earth may be due to the use of an inordinate amount of energy in order to maintain anything like adequate heat regulation. Another instance is the movement of birds and mammals to favorable environments, often referred to loosely as the migrational instinct. It has even been proposed that the gregarious "sociability" of organisms of the same species has its basic condition in reactions motivated by inadequate heat regulation. As these organisms moved about restlessly in the cold, they chanced to form a huddle; and the heat radiating from one another's bodies was sufficient to alleviate the tissue condition and allow the organisms to come to rest. While this hypothesis may seem a bit far-fetched, there is no doubt that inadequate heat regulation is one of the basic motivational excitants, operating in a manner similar to other tissue conditions heretofore discussed.