• Stress:Any factor that interferes with the normal limits of operation of an organism.
• Homeostasis: In a physiologic sense, the maintenance of normal limits of body functioning.
• Acclimation: short-term physiologic responses to a stress, usually within minutes or hours.
(sweating when hot)
• Acclimatization: Long-term physiologic responses to a stress, usually taking from days to
months. (increase in red blood cell production after moving to a high-altitude environment)
• Developmental acclimatization: Changes in organ or body structure that occur during the
physical growth of any organism. (an increase in chest size that occurs when a person moves to
• Plasticity: The ability of an organism to respond physiologically or developmentally to
• Vasoconstriction: The narrowing of blood vessels, which reduces blood flow and heat loss.
• Vasodilation: The opening of blood vessels, which increases blood flow and heat loss.
• The body loses heat in four ways:
◦ Radiation: heat flow from objects in the form of electromagnetic radiation. The body
removes heat through radiation but also picks up heat radiated by other objects.
◦ Convection: the removal or gain of heat through air molecules. Heat flows from a warm
object to a cooler object.
◦ Conduction: heat exchange through physical contact with another object, such as the ground
◦ Evaporation: loss of heat through the conversion of water to vapor.(Sweat). This is the only