Morphine: An Introduction | Discovery and Synthesis of Morphine | Addiction and Opiate Receptors | Morphine Affects History: Modern Pharmacology | History Affects Morphine: The Hypodermic Needle | History Affects Morphine II: Cultural Antipathy and Anti-Narcotics Law| References
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Morphine, as an opiate compound, affects the body at sites known as opiate receptors. These are located throughout the nervous system, mainly in the brain, spinal cord, and gut (C&E News)
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Opiate receptors themselves were discovered in 1973, and as of today, three types are known: μ, κ, and σ receptors. Morphine has an affinity for the μ receptor
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Such receptors are effectively turned on by morphine molecules; morphine molecules interact with receptors in what is known as a structure-activity relationship, thereby competing with and blocking endorphin molecules – short for endogenous morphoids – from binding there. This creates an imbalance in the synaptic cleft, and pain-relieving morphine molecules are in abundance; not surprisingly, this creates both the “analgesic (painkilling) and euphoric (exaggerated happiness) effects for which morphine is famous” (Waldron)
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Why can morphine compete with endorphin molecules? The answer is such that morphine, like endorphin molecules, contains a “β-phenylethylamine unit,” something that lets both morphine and endorphins bind to the opiate receptor
Opiate receptor activity in the human brain:
(http://www.sfn.org/skins/main/images/brainbriefings/opiate_illus.gif)
