Acclimatization is the process of an organism adjusting to chronic change in its environment, often involving temperature, moisture, food, often relating to seasonal
climatechanges. (In laboratory conditions, this process is controlled to one variable change only and is termed "Acclimation"). Acclimatization usually occurs in a short time, and within one organism's lifetime (compare adaptation). This may be a discrete occurrence or may instead represent part of a periodic cycle, such as a mammal shedding heavy winter furin favor of a lighter summer coat. Where acclimatization occurs naturally, some authors have used acclimationto describe the process of an organism being forced to adjust to changes in their environment by artificial means, such as in a laboratory setting. [Schmidt-Nielsen, Knut. Animal Physiology: adaptation and environment. 4th Ed. Cambridge ; New York : Cambridge University Press, 1990.]
Many plants, such as
maple trees, irises, and tomatoes, can survive freezing temperatures if the temperature gradually drops lower and lower each night over a period of days or weeks. The same drop might kill them if it occurred suddenly. This process is called "hardening" and involves several changes, such as a decrease in the water content and an increase in the sugar content of the plant, lowering the freezing pointof sap.
Animals acclimate in many ways.
Sheepgrow very thick woolin cold, damp climates. Fishare able to adjust only gradually to changes in water temperature and quality. Tropical fish sold at pet stores are often kept in acclimation bagsuntil this process is complete.
When humans move from a
coolor temperateenvironment to a hot, dry desertenvironment or vice versa, they should spend up to seven days acclimatizing to the change in their environment. This lets the body make internal adjustments ("see homeostasis") to compensate for the change in environment conditions. If the acclimatization process is ignored, then the person is at higher risk for heat related injuries ( heat stroke, heat cramp, pneumonia).
high altitudecontinues for months or even years after initial ascent, and ultimately enables humans to survive in an environment that, without acclimatization, would kill them. Humans who migrate permanently to a higher altitude naturally acclimatize to their new environment by developing an increase in the number of red blood cellsto increase the oxygencarrying capacity of the blood, in order to compensate for lower levels of oxygenin the air. [cite web | author=Kenneth Baillie and Alistair Simpson | title=Altitude oxygen calculator | url=http://www.altitude.org/calculators/oxygencalculator/oxygencalculator.htm | publisher=Apex (Altitude Physiology EXpeditions) | accessdate=2006-08-10 - Altitude physiology model]
World Bookencyclopedia 1989
*US Army - Heat Acclimation Guide [http://www.usariem.army.mil/download/heatacclimatizationguide.pdf]
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