Changes

At low ambient temperatures, the body must produce more heat than at warmer temperatures, just to maintain a stable core temperature.  With time, the metabolic rate of animals continuously exposed to the cold will increase gradually without any increase in muscle activity.  This is termed '''non-shivering thermogenesis''' and is primarily attributed to:

At low ambient temperatures, the body must produce more heat than at warmer temperatures, just to maintain a stable core temperature.  With time, the metabolic rate of animals continuously exposed to the cold will increase gradually without any increase in muscle activity.  This is termed '''non-shivering thermogenesis''' and is primarily attributed to:

* increased activity of the [[Nervous System - PNS - Anatomy & Physiology|sympathetic nervous system]]  

* increased activity of the [[Nervous System - PNS - Anatomy & Physiology|sympathetic nervous system]]  

* increased secretion of [[Endocrine System - Thyroid Gland - Anatomy & Physiology|thyroid hormones]]

* increased secretion of [[Thyroid Gland - Anatomy & Physiology|thyroid hormones]]

==Physiology==

==Physiology==