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Cellular Injury During Ischemia
Neuronal Function: Importance of Oxygen and Glucose
A neuron consists of a cell body, which contains
a nucleus, and one or more extensions protruding from the
cell body. Dendrites receive nerve impulses from other
neurons or from sensory receptors. The axon carries
the nerve impulses (action potential) away from the cell body
to another neuron or to an effector organ such as a muscle.
 A
stimulus affects the axon by changing the permeability of
the axon to positive ions. The influx of positive ions
reduces the electrical potential across one segment of the
membrane (depolarization). The change in electrical
potential in the first part of the axon triggers a change
in electrical potential in the adjacent segment of the axon
such that the impulse travels along the axon as a self-generating
chain reaction.
At most synapses, arrival of the impulse at
the presynaptic terminal leads to release of neurotransmitter,
which crosses the synapse to interact with receptors on the
membrane of the postsynaptic cell. This interaction
opens ion-specific channels in the postsynaptic membrane,
changing the membrane's permeability for positive ions.
The transient change in voltage induced by the
action potential is determined by the concentration of ions
on either side of the cell membrane. Maintaining these
ionic gradients is an energy-consuming process that requires
a constant supply of glucose and oxygen to the neuron.
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