| The limbic system, the main regulator of emotion,
surrounds the brain stem just below the cerebral cortex. Opiate receptors
are more dense in the limbic system than anywhere else in the body, consistent
with the strong effects opioids have on emotional behavior. The most
notable emotional effect of opioids is euphoria, an elevated feeling of
care-free and well being (Snyder, 1996).
Endorphins are released in the limbic system when humans experience pleasure--during eating, exercise, and romantic endeavors (Hawkes, 1992). The level of euphoria that is produced during each of these events has been shaped by millions of years of evolution. Pleasurable feelings are |
part of the motivation system the body uses to
inspire a person to fulfill his nutritional and sexual needs (Schick-Schadel
Hospital).
Euphoria stimulated by opioids can be characterized as
"too much of a good thing." Because opioids are not rapidly broken
down after acting, they continue to activate receptors for extended periods
and produce a level of euphoria that is considerably more intense than
that initiated by endorphins (Snyder, 1978). For similar reasons,
regular opioid users develop tolerance
and dependency. |
 |
| A simplified diagram of the brain's reward system. When one of the body's survival needs (on the left) is satisfied, endorphins stimulate the reward centers in the limbic system by activating opiate receptors. Ths result is a pleasurable feeling. When opioids stimulate reward centers, a more profound euphoria is felt and the brain's motivation system for fulfilling survival needs is bypassed. Image adapted from Schick-Schadel Hospital. Used with permission. |
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This site was created during the fall semester of 1999 by Wes
Self, a student at
Davidson College, as part of an assignment in Biology 312 (Animal Physiology). Questions, comments and suggestions are appreciated at weself@davidson.edu |