Excitotoxicity cellular events during

FIGURE 10-28. Cellular events occurring during excitotoxicity (part 2). The internal milieu of a neuron is very sensitive to calcium, as a small increase in calcium concentration will alter all sorts of enzyme activity, as well as neuronal membrane excitability. If calcium levels rise too much, they will begin to activate enzymes that can be dangerous for the cell owing to their ability to trigger a destructive chemical cascade. 

FIGURE 10—29. Cellular events occurring during excitotoxicity (part 3). Once excessive glutamate causes too much calcium to enter the neuron and calcium activates dangerous enzymes, these enzymes go on to produce troublesome free radicals. Free radicals are chemicals that are capable of destroying other cellular components, such as organelles and membranes, by destructive chemical reactions. 

FIGURE 10-30. Cellular events occurring during excitotoxicity (part 4). As the calcium accumulates in the cell, and the enzymes produce more and more free radicals, they begin to indiscriminately destroy parts of the cell, especially its neuronal and nuclear membranes and critical organelles such as energy-producing mitochondria. 

FIGURE 10-31. Cellular events occurring during excitotoxicity (part 5). Eventually, the damage is so great that the free radicals essentially destroy the whole neuron. 

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