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Chapter 5.4 Life in Cold Environment

BOOK TITLE: Understanding Medical Physiology: A Textbook for Medical Students

Author
1. Bijlani R.L.
ISBN
9788180612213
DOI
10.5005/jp/books/10999_40
Edition
3/e
Publishing Year
2004
Pages
4
Author Affiliations
1. All India Institute of Medical Sciences, New Delhi
Chapter keywords
sympathetic stimulation, environmental temperature, thermoregulatory responses, vasodilatation, physiological responses, behavioural response, seasonal fluctuation, hermosensors, wind velocity, vasoconstriction, metabolic rate, coagulation characteristics, alternating pattern, vestigial response, glucocorticoids, high humidity, microenvironment

Abstract

This chapter discusses life in cold environment, where the severity of cold depends not only on the environmental temperature but also on wind velocity and humidity. Human responses to acute exposure to extreme cold are mostly directed at maintenance of core temperature. The initial response to cold is vasoconstriction. Vasoconstriction reduces blood flow and hence leads to accumulation of carbon dioxide and other metabolites characteristic of tissue hypoxia. Glucocorticoids improve the capacity of the body to withstand any type of stress, including cold stress. Peculiarly human behavioural responses include also seeking heavy clothing, and warming the microenvironment with heaters. Low temperature impairs coagulation but not sufficiently to eliminate the need for an anticoagulant. Thyroid hormones raise the metabolic rate and heat production in the body. Prolonged freezing cold may lead to death of tissues at the peripheral parts of the body, such as fingertips, toes and earlobes.

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