The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
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The human body is able to actively regulate its internal temperature somewhere between 98°F (36.6°C) and 100°F (37.7°C) in spite of various forces that act to cool off the body.
These mechanisms operate through a control region of the brain called hypothalamus, which contains the mechanisms to control the internal temperature and sensors to monitor the body.
The sensors of temperature regulation are on the skin surface and within the body. These all "report" to the hypothalamus.
The body is monitored to gauge the ebb and flow that can occur by various means. Evaporation of liquid draws heat away, as does loss of heat by moving air (convection) and by the radiation of heat from the body surface to the cooler surrounding air. The body can also be heated by a source of radiation. For example, sitting out in the sun on a summer day will warm up the body. Another form of heat loss is via the transfer from the body directly to a solid surface, such as a tile floor. This is heat loss by conduction.
If the internal temperature increases out of the normal range the hypothalamus acts to maximize heat loss by triggering the production of sweat. The evaporation of the sweat cools the body. If this is not sufficient to bring the temperature back to normal, the degree of sweating can be increased. On the other hand, if body temperature drops below the normal range, a number of responses can be triggered by the hypothalamus to minimize heat loss and maximize heat production. Vasoconstriction (shrinkage of the diameter of blood vessels) can occur. This decreases the flow of blood (and so of heat) to the skin. Sweating can be ended. The body can begin to shiver, which heats up the muscles. The secretion of compounds such as norepinephrine, epinephrine, and thryoxine can be stimulated. These compounds also increase heat production.
Temperature regulation also accounts for the temperature of the surrounding air. In cold winter conditions, the body will monitor so as to maintain the proper internal temperature in the core of the body (head and truck). The limbs will be allowed to get cooler before a regulatory alteration is made. In the warm summer months, the zone of the internal temperature that is maintained covers a larger area of the body, excluding only the hands and feet. Body fat provides further temperature regulation via insulation.