CAROL & MIKE WERNER / VISUALS UNLIMITED, INC / SCIENCE PHOTO LIBRARY CAROL & MIKE WERNER / VISUALS UNLIMITED, INC / SCIENCE PHOTO LIBRARY
Biomedical illustration of Alzheimer's disease. The enzyme gamma secretase snips the amyloid precursor protein to produce beta amyloid. Oligomers formed of beta amyloid are thought to play a key role in the development of Alzheimer's disease. Oligomers attach themselves to dendrites at synapses, thus interfering with the activity of neurotransmitters. Oligomers are also a major constituent of the sticky plaque which adheres to the surfaces of neurons. Plaque was originally seen as a major cause of of nerve damage although some researchers now believe it to be a protective reaction to confine beta amyloid and prevent further damage. Excessive plaque buildup may still be damaging, however. A cross-ection of a nerve cell (lower right) illustrates clumps of.
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