In human being, the least useful physiological response to low environmental temperature is
Thermoregulation in humans is an impoant aspect of homeostasis. In thermoregulation, body heat is generated mostly in the deep organs, especially the liver, brain, and hea, and in contraction of skeletal muscles. Humans have been able to adapt to a great diversity of climates, including hot humid and hot arid and cold climates. For humans, adaptation to varying climatic conditions includes both physiological mechanisms resulting from evolution and behavioral mechanisms resulting from conscious cultural adaptations.Shivering - Muscles can also receive messages from the thermoregulatory center of the brain (the hypothalamus) to cause shivering. This increases heat production as respiration is an exothermic reaction in muscle cells. Shivering is more effective than exercise at producing heat because the animal (includes humans) remains still. Vasoconstriction - Aerioles carrying blood to superficial capillaries under the surface of the skin can shrink (constrict), thereby rerouting blood away from the skin and towards the warmer core of the body. This prevents blood from losing heat to the surroundings and also prevents the core temperature dropping fuher. This process is called vasoconstriction. Thyroxine - An iodine-containing hormone, produced by the thyroid gland, that increases the rate of cell metabolism.Piloerection - The minute muscles under the surface of the skin called arrector pili muscles (attached to an individual hair follicle) contract (piloerection), lifting the hair follicle upright. This makes the hairs stand on end, which acts as an insulating layer, trapping heat.Ref: Ganong&;s review of medical physiology-24th edition, page no-318
Shivering
Vasoconstriction
Release of thyroxine
Piloerection
Endocrinology