FIGHT-FLIGHT-FREEZE

 

The hypothalamus controls a wide range of functions. It directs the “fight or flight” response of the autonomic nervous system. Fear or excitement causes signals to travel to the hypothalamus, which triggers a rapid heartbeat, faster breathing, widening of the pupils, and increased blood flow. The hypothalamus monitors blood glucose levels and the body’s water content to regulate appetite for food or drink. It regulates sleep and sexual behavior.

 

The hypothalamus plays an important role in regulating feeding behavior. Experiments performed on rats demonstrate that if the middle of the hypothalamus is damaged, the rat overeats and becomes obese; damage in the lower part causes the rat to refuse to eat and starve. The role of the human hypothalamus is less important than in rodents because conscious decisions play a greater part in human processes such as eating and drinking. For example, it has been shown that custom and habit have a greater influence over the amount eaten than actual hunger. The hypothalamus has an effect on the cardiovascular system and the rest of the autonomic nervous system. This effect is vital for the coordination of mind and body; for example, it is responsible for the physical changes required before exercise.