The Human Brain : From Neurone to Nervous System

Hypothalamus and Thermoregulation

  1. Body temperature is controlled within a fairly narrow range in mammals including humans. Regulation of body temperature is acheived by balancing heat generation within the body and heat loss mainly through the skin. These functions of the hypothalamus require
    • connections with autonomic pathways that regulate the loss of heat by their action on skin blood vessels and sweat glands.
    • its influence over the skeletal musculature in the process of shivering, which increases metabolism and therefore body temperature.
    • and the production of releasing factors that regulate anterior pituitary hormones that influence metabolism in the longer term.
  2. Temperature -sensitive neurons in the anterior hypothalamus determine whether the body retains heat or dissipates it.
  3. Fever occurs during infections because of the release of endogenous pyrogens that act on pre-optic areas of the anterior hypothalamus. They appear to raise the 'set-point' (normally ~37 degrees C)around which body termperature is regulated, and result in the generation of heat ( shivering) and its retention by constriction in skin blood vessels.
  4. Hypothermia occurs when the body cools excessively due to reduced metabolism or exposure to cold (e.g. as in immersion in cold water).