Answer to Question #126735 in Human Anatomy and Physiology for Hannah

Question

Describe how your body will react to decrease in temperature

Answer 1

1. Vasoconstriction. Sympathetic centers in the posterior hypothalamus cause vasoconstriction of cutaneous blood vessels, which leads to reduced blood flow to the skin. This reduces the loss of heat by radiation to the environment.

2. Shivering; The primary motor center for shaking in the posterior hypothalamus is stimulated, and shivering occurs. This involuntary contraction of muscles generates large amounts of heat, which compensate for the decreased body temperature.

3. Hormonal thermogenesis; Hypothalamus secretes a thyrotropin-­releasing hormone, which the effect is the discharge of thyroid­stimulating hormone thus increasing the release of thyroxine. Thyroxine speeds up the metabolic activities in the body increasing heat production.

 Sympathetic centers stimulate the secretion of adrenaline, which accelerates cellular metabolic activities, thus increasing heat production. 

4. The arrector pili muscle contract lifting the hair follicles upright. This makes the hair ends stand erect. This enables them to trap a layer of air, which acts as an insulating layer reducing heat loss.

5. The rate of sweating is reduced. This reduces the amount of heat being lost from the surface of the skin by evaporation of the sweat.