Posted by Q (198.64.206.92) on January 27, 2000 at 01:37:49:
In Reply to: Time, Temperature and the Hypothalmus. Pain Center? posted by Q on January 26, 2000 at 03:53:36:
When an injury occurs, signals pass along nerve pathways concerned with pain, first to the spinal cord and then to the THALMUS in the brain; there pain is PERCEIVED.
Certain diseases, such as arthritis and extensive cancer, may set off these same pain mechanisms.
The signals are set off by stimulation of special nerve endings -- by pressure, heat, OR RELEASE OF CHEMICALS, including prostaglandins, by damaged cells.
Within the brain and spinal cord, pain signals pass between nerve cells by means of CHEMICALS that cross between the cells.
A surgical procedure which cuts nerve fibers in the THALMUS may be used to prevent the perception of pain.
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The HYPOTHALMUS is situated directly under the thalmus. The hypothalmus has nerve connections to most other regions of the nervous systems. It exerts overall control over the sypathetic nervous system (SNS).
When we are suddenly frightened or excited, signals are sent from higher regions of the brain to the hypothalmus, which INITIATES SNS activity, such as faster heart beat, increased breathing, widening of the pupils of the eyes and increased blood flow to the muscles (known as "fight or flight").
The hypothalmus is also involved in regulating sleep, in motivating sexual behavior, and in determining mood and the experience of emotions.
The hypothalmus coordinates the endocrine (harmonal) system and thereby indirectly controls the adrenal cortex.
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Reference -- American Medical Association (AMA) Encyclopedia of Medicine - 1989